ABBOTT LABORATORIES
SC 14D1, 1996-04-04
PHARMACEUTICAL PREPARATIONS
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<PAGE>
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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                              --------------------
                                 SCHEDULE 14D-1
               Tender Offer Statement Pursuant to Section 14(d)(1)
                     of the Securities Exchange Act of 1934
                              --------------------
                                 MediSense, Inc.
                            (Name of Subject Company)

                              AAC Acquisition, Inc.
                          a wholly owned subsidiary of
                               Abbott Laboratories
                                    (Bidder)

                                  Common Stock
                                       and
                              Class B Common Stock
                         (Title of Class of Securities)
                                    584960108
                      (CUSIP Number of Class of Securities)
                              --------------------
                                 Jose M. de Lasa
                        Senior Vice President, Secretary 
                               and General Counsel
                               Abbott Laboratories
                              100 Abbott Park Road
                        Abbott Park, Illinois 60064-3500
                                 (847) 937-6100

                                 with a copy to:

                                Robert A. Helman
                              Mayer, Brown & Platt
                            190 South LaSalle Street
                             Chicago, Illinois 60603
                                 (312) 782-0600
            (Name, Address and Telephone Number of Person Authorized
           to Receive Notices and Communications on Behalf of Bidder)

                            CALCULATION OF FILING FEE
- --------------------------------------------------------------------------------
     Transaction Valuation*                       Amount of Filing Fee
- --------------------------------------------------------------------------------
          $876,015,000                                 $175,203 
- --------------------------------------------------------------------------------

*    For purposes of calculating the filing fee only.  This amount assumes the
     purchase of 19,467,000 shares of Common Stock and Class B Common Stock
     (together, the "Shares") of the subject company at $45.00 in cash per
     Share.
/ /  Check box if any part of the fee is offset as provided by Rule 0-11(a)(2)
     and identify the filing with which the offsetting fee was previously paid. 
     Identify the previous filing by registration statement number, or the Form
     or Schedule and the date of its filing.

          Amount Previously Paid:       Not Applicable.
          Form or Registration Number:  Not Applicable.
          Filing Party:       Not Applicable.
          Date Filed:         Not Applicable.
                                                                                
                               Page 1 of 6 Pages
                       Exhibit Index is located on Page 4

<PAGE>

CUSIP No.:  584960108                 14D-1                 Page 2 of 6 Pages



1.   Name of Reporting Person:  AAC Acquisition, Inc.
     S.S. or I.R.S. Identification Nos. of Above Person:  None.
     Name of Reporting Person:  Abbott Laboratories
     S.S. or I.R.S. Identification Nos. of Above Person:  36-0698440
                                                                                

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2.   Check the Appropriate Box if a Member of a Group:                 (a)   / /
                                                                       (b)   / /
                                                                                

- --------------------------------------------------------------------------------

3.   SEC Use Only:
                                                                                

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4.   Sources of Funds:  WC
                                                                                

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5.   Check if Disclosure of Legal Proceedings is Required Pursuant to 
     Items 2(e) or 2(f):                                                     / /
                                                                                

- --------------------------------------------------------------------------------

6.   Citizenship or Place of Organization:  Massachusetts (AAC Acquisition,
     Inc.); Illinois (Abbott Laboratories)
                                                                                

- --------------------------------------------------------------------------------

7.   Aggregate Amount Beneficially Owned by Each Reporting Person:   0 Shares 
                                                                                

- --------------------------------------------------------------------------------

8.   Check if the Aggregate in Row (7) Excludes Certain Shares:              / /
                                                                                

- --------------------------------------------------------------------------------

9.   Percent of Class Represented by Amount in Row (7):   0.0%
                                                                                

- --------------------------------------------------------------------------------

10.  Type of Reporting Person:  CO (AAC Acquisition, Inc.)
                                 CO (Abbott Laboratories)
                                                                                

- --------------------------------------------------------------------------------


                                        2

<PAGE>


ITEM 1.   SECURITY AND SUBJECT COMPANY.

     (a)  The name of the subject company is MediSense, Inc., a Massachusetts
corporation (the "Company"), which has its principal executive offices at 266
Second Avenue, Waltham, Massachusetts 02154.  Capitalized terms used in this
Schedule 14D-1 and not defined herein shall have the meanings set forth in the
Offer to Purchase dated April 4, 1996 (the "Offer to Purchase") attached hereto
as Exhibit (a)(1).

     (b)  The information set forth in the "Introduction" of the Offer to
Purchase is incorporated herein by reference.

     (c)  The information set forth in "The Tender Offer - 6.  Price Range of
the Shares" of the Offer to Purchase is incorporated herein by reference.

ITEM 2.   IDENTITY AND BACKGROUND.

     (a)-(d) and (g)  The information set forth in "Introduction" and "The
Tender Offer - 8. Certain Information Concerning the Purchaser and Parent" of
the Offer to Purchase is incorporated herein by reference.

     (e) and (f)  During the last five years, neither Abbott Laboratories, an 
Illinois corporation ("Parent"), nor  AAC Acquisition, Inc., a Massachusetts 
corporation and wholly owned subsidiary of Parent (the "Purchaser"), nor, to 
the best of their knowledge, any of the individuals listed in Schedule I of 
the Offer to Purchase has (i) been convicted in a criminal proceeding or (ii) 
been a party to a civil proceeding of a judicial or administrative body of 
competent jurisdiction and, as a result of such proceeding, was or is subject 
to a judgment, decree or final order enjoining future violations of, or 
prohibiting activities subject to, federal or state securities laws or 
finding any violation of such laws.

ITEM 3.   PAST CONTACTS, TRANSACTIONS OR NEGOTIATIONS WITH THE SUBJECT COMPANY.

     (a)-(b)   The information set forth in "The Tender Offer - 8. Certain
Information Concerning the Purchaser and Parent" and "The Tender Offer - 9.
Background of the Merger and the Offer" of the Offer to Purchase is incorporated
herein by reference.  

ITEM 4.   SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

     (a)-(b)   The information set forth in "The Tender Offer - 11. Source 
and Amount of Funds" of the Offer to Purchase is incorporated herein by 
reference.

     (c)  None

ITEM 5.   PURPOSE OF THE TENDER OFFER AND PLANS OR PROPOSALS OF THE BIDDER.

     (a)-(g)  The information set forth in the "Introduction," "The Tender 
Offer - 10. Purpose of the Offer; the Merger Agreement" and "The Tender Offer 
- - 12. Certain Effects of the Offer" of the Offer to Purchase is incorporated 
herein by reference.

ITEM 6.   INTEREST IN SECURITIES OF THE SUBJECT COMPANY.

     (a)-(b)   None.



                                        3

<PAGE>

ITEM 7.   CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT
          TO THE SUBJECT COMPANY'S SECURITIES.

     The information set forth in "The Tender Offer - 8. Certain Information
Concerning Purchaser and Parent" and "The Tender Offer - 10. Purpose of the
Offer; the Merger Agreement" of the Offer to Purchase is incorporated herein by
reference.

ITEM 8.   PERSONS RETAINED, EMPLOYED OR TO BE COMPENSATED.

     The information set forth in "The Tender Offer - 16. Fees and Expenses" of
the Offer to Purchase is incorporated herein by reference.

ITEM 9.   FINANCIAL STATEMENTS OF CERTAIN BIDDERS.

     The information set forth in "The Tender Offer - 8. Certain Information
Concerning Purchaser and Parent" of the Offer to Purchase is incorporated herein
by reference. 

     This incorporation by reference herein of the above referenced financial
information does not constitute an admission that such information is material
to a decision by a stockholder of the Company whether to sell, tender or hold
Shares being sought in this tender offer.

ITEM 10.    ADDITIONAL INFORMATION.

     (a)  None.

     (b)-(d) The information set forth in "The Tender Offer - 12. Certain 
Effects of the Offer" and "The Tender Offer - 15. Certain Legal Matters; 
Regulatory Approvals" of the Offer to Purchase is incorporated herein by 
reference.

     (e)  None.

     (f)  Reference is hereby made to the Offer to Purchase and the related
Letter of Transmittal, copies of which are attached hereto as Exhibits (a)(1)
and (a)(2), respectively, and which are incorporated herein in their entirety by
reference.

ITEM 11.  MATERIAL TO BE FILED AS EXHIBITS.

     (a)(1)    Offer to Purchase dated April 4, 1996.

     (a)(2)    Form of Letter of Transmittal.

     (a)(3)    Form of Letter to Clients dated April 4, 1996.

     (a)(4)    Form of Letter to Brokers, Dealers, Commercial Banks, Trust
               Companies and Other Nominees dated April 4, 1996.

     (a)(5)    Form of Notice of Guaranteed Delivery.

     (a)(6)    Guidelines for Certification of Taxpayer Identification Number on
               Substitute Form W-9.

     (a)(7)    Form of Summary Advertisement.

     (a)(8)    Form of Press Release.

     (a)(9)    Form of Letter to MediSense, Inc. stockholders.

     (b)       None.


                                        4

<PAGE>

     (c)(1)    Agreement and Plan of Merger among MediSense, Inc., Abbott
               Laboratories and AAC Acquisition, Inc. dated as of March 29,
               1996.

     (c)(2)    Confidentiality Agreement between MediSense, Inc. and Abbott
               Laboratories dated as of March 13, 1996.

     (d)       None.

     (e)-(f)   Not Applicable.


                                        5

<PAGE>

                                   SIGNATURES


     After due inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.


Dated:  April 4, 1996.                  AAC ACQUISITION, INC.


                                        By: /s/ Gary P. Coughlan
                                            ------------------------------------
                                        Name:  Gary P. Coughlan
                                        Title: Vice President and Treasurer

                                        ABBOTT LABORATORIES


                                        By: /s/ Gary P. Coughlan
                                            ------------------------------------
                                        Name:  Gary P. Coughlan
                                        Title: Senior Vice President, Finance
                                               and Chief Financial Officer


                                        6

<PAGE>

                                  EXHIBIT INDEX


                                                                    Sequentially
                                                                      Numbered  
Exhibit        Description                                              Page    
- -------        -----------                                          ------------

(a)(1)         Offer to Purchase dated April 4, 1996 . . . . . . . . .
(a)(2)         Form of Letter of Transmittal . . . . . . . . . . . . .
(a)(3)         Form of Letter to Clients dated April 4, 1996 . . . . .
(a)(4)         Form of Letter to Brokers, Dealers, . . . . . . . . . .
                    Commercial Banks, Trust Companies and
                    Other Nominees, dated April 4, 1996. . . . . . . .
(a)(5)         Form of Notice of Guaranteed Delivery . . . . . . . . .
(a)(6)         Guidelines for Certification of Taxpayer 
                    Identification Number on Substitute Form W-9 . . .
(a)(7)         Form of Summary Advertisement . . . . . . . . . . . . .
(a)(8)         Form of Press Release . . . . . . . . . . . . . . . . .
(a)(9)         Form of Letter to MediSense, Inc. stockholders. . . . .
(b)            None  . . . . . . . . . . . . . . . . . . . . . . . . .
(c)(1)         Agreement and Plan of Merger among MediSense, Inc.,
                    Abbott Laboratories and AAC Acquisition, Inc. 
                    dated as of March 29, 1996 . . . . . . . . . . . .
(c)(2)         Confidentiality Agreement between MediSense, Inc. 
                    and Abbott Laboratories  
                    dated as of March 13, 1996 . . . . . . . . . . . .
(d)            None  . . . . . . . . . . . . . . . . . . . . . . . . .
(e)-(f)        Not applicable. . . . . . . . . . . . . . . . . . . . .


                                        7
 

<PAGE>
                           OFFER TO PURCHASE FOR CASH
        ALL OUTSTANDING SHARES OF COMMON STOCK AND CLASS B COMMON STOCK
 
                                       OF
 
                                MEDISENSE, INC.
 
                                       AT
 
                              $45.00 NET PER SHARE
 
                                       BY
 
                             AAC ACQUISITION, INC.
 
                          A WHOLLY OWNED SUBSIDIARY OF
 
                              ABBOTT LABORATORIES
 
    THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK
       CITY TIME, ON WEDNESDAY, MAY 1, 1996 UNLESS THE OFFER IS EXTENDED.
 
    THE  OFFER IS CONDITIONED UPON, AMONG  OTHER THINGS, (1) THERE BEING VALIDLY
TENDERED AND  NOT PROPERLY  WITHDRAWN PRIOR  TO THE  EXPIRATION OF  THE OFFER  A
NUMBER  OF SHARES OF  COMMON STOCK AND  CLASS B COMMON  STOCK (COLLECTIVELY, THE
"SHARES") OF  MEDISENSE,  INC. (THE  "COMPANY")  WHICH CONSTITUTES  AT  LEAST  A
MAJORITY  OF  THE OUTSTANDING  SHARES  ON A  FULLY  DILUTED BASIS  (THE "MINIMUM
CONDITION"), AND (2)  THE EXPIRATION  OR TERMINATION OF  ANY APPLICABLE  WAITING
PERIOD  UNDER  THE  HART-SCOTT-RODINO  ANTITRUST IMPROVEMENTS  ACT  OF  1976, AS
AMENDED (THE "HSR ACT"). THE OFFER IS ALSO SUBJECT TO OTHER TERMS AND CONDITIONS
CONTAINED IN THIS  OFFER TO  PURCHASE. SEE INTRODUCTION  AND SECTIONS  1 AND  13
HEREOF.
 
    THE  OFFER IS BEING MADE IN CONNECTION WITH THE AGREEMENT AND PLAN OF MERGER
DATED AS OF MARCH 29, 1996 AMONG THE COMPANY, ABBOTT LABORATORIES ("PARENT") AND
AAC  ACQUISITION,  INC.   ("PURCHASER"),  PURSUANT  TO   WHICH,  FOLLOWING   THE
CONSUMMATION  OF THE OFFER, PURCHASER  WILL BE MERGED WITH  AND INTO THE COMPANY
(THE "MERGER") AND THE COMPANY WILL BECOME A WHOLLY OWNED SUBSIDIARY OF  PARENT.
THE  BOARD OF DIRECTORS OF  THE COMPANY UNANIMOUSLY HAS  APPROVED THE MERGER AND
RECOMMENDS THAT STOCKHOLDERS OF  THE COMPANY ACCEPT THE  OFFER AND TENDER  THEIR
SHARES  PURSUANT TO  THE OFFER.  THE OFFER IS  BEING EFFECTED  TO FACILITATE THE
MERGER. SEE "RECOMMENDATION OF THE COMPANY'S BOARD OF DIRECTORS."
                            ------------------------
 
                                   IMPORTANT
 
    Any stockholder desiring to tender all or any portion of such  stockholder's
shares  of common  stock, $.01  par value  per share  (the "Common  Stock"), and
shares of class B common  stock, $.01 par value per  share (the "Class B  Common
Stock"  and, together  with the Common  Stock, the "Shares"),  should either (1)
complete and  sign  the  Letter  of Transmittal  (or  a  facsimile  thereof)  in
accordance with the instructions in the Letter of Transmittal and deliver it and
any   other  required  documents  to  the  Depositary  and  either  deliver  the
certificate(s) representing such Shares to the Depositary along with the  Letter
of  Transmittal or tender  such Shares pursuant to  the procedure for book-entry
transfer set forth in Section 3 hereof or (2) request such stockholder's broker,
dealer,  commercial  bank,  trust  company  or  other  nominee  to  effect   the
transaction for such stockholder. Any stockholder whose Shares are registered in
the  name of a broker,  dealer, commercial bank, trust  company or other nominee
must contact  such  broker, dealer,  commercial  bank, trust  company  or  other
nominee if such stockholder desires to tender such Shares.
 
    A   stockholder  who  desires  to   tender  Shares  and  whose  certificates
representing such Shares  are not  immediately available, or  who cannot  comply
with  the procedure for book-entry  transfer on a timely  basis, may tender such
Shares by following the procedures for guaranteed delivery set forth in  Section
3.
 
    Questions  and requests for assistance or additional copies of this Offer to
Purchase, the Letter of Transmittal and the Notice of Guaranteed Delivery may be
directed to the  Dealer Managers or  the Information Agent  at their  respective
addresses  and telephone numbers  set forth on  the back cover  of this Offer to
Purchase. Additional copies of this Offer to Purchase, the Letter of Transmittal
and the Notice of Guaranteed Delivery may be obtained from the Information Agent
or from brokers, dealers, commercial banks or trust companies.
                            ------------------------
 
                     The Dealer Managers for the Offer are:
                              GOLDMAN, SACHS & CO.
                                ---------------
              The date of this Offer to Purchase is April 4, 1996
<PAGE>
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                                                               PAGE
                                                                                                             ---------
<C>        <S>                                                                                               <C>
INTRODUCTION...............................................................................................          1
RECOMMENDATION OF THE COMPANY'S BOARD OF DIRECTORS.........................................................          2
THE TENDER OFFER...........................................................................................          2
       1.  Terms of the Offer; Extension of Tender Period; Termination; Amendment..........................          2
       2.  Acceptance for Payment and Payment for Shares...................................................          4
       3.  Procedure for Tendering Shares..................................................................          4
       4.  Withdrawal Rights...............................................................................          7
       5.  Certain Federal Income Tax Consequences of the Offer and the Merger.............................          7
       6.  Price Range of the Shares.......................................................................          8
       7.  Certain Information Concerning the Company......................................................          9
       8.  Certain Information Concerning Purchaser and Parent.............................................          9
       9.  Background of the Merger and the Offer..........................................................         11
      10.  Purpose of the Offer; the Merger Agreement......................................................         11
      11.  Source and Amount of Funds......................................................................         17
      12.  Certain Effects of the Offer....................................................................         17
      13.  Certain Conditions of the Offer.................................................................         18
      14.  Dividends and Distributions.....................................................................         19
      15.  Certain Legal Matters; Regulatory Approvals.....................................................         19
      16.  Fees and Expenses...............................................................................         21
      17.  Miscellaneous...................................................................................         21
Schedule I -- Information Concerning the Directors and Executive Officers of Parent and Purchaser..........
                                                                                                                   I-1
Annex I -- Agreement and Plan of Merger....................................................................          1
Annex II -- Fairness Opinion of Alex. Brown & Sons Incorporated............................................     A-II-1
</TABLE>
 
                                      (i)
<PAGE>
To the Stockholders of MediSense, Inc.:
 
                                  INTRODUCTION
 
    AAC  Acquisition,  Inc.,  a Massachusetts  corporation  ("Purchaser"),  is a
wholly  owned  subsidiary  of  Abbott  Laboratories,  an  Illinois   corporation
("Parent"). Purchaser hereby offers to purchase all of the outstanding shares of
common  stock, $.01  par value per  share (the  "Common Stock"), and  all of the
outstanding shares of class B common stock, par value $.01 per share (the "Class
B Common  Stock"  and,  together  with  the  Common  Stock,  the  "Shares"),  of
MediSense,  Inc.,  a Massachusetts  corporation (the  "Company"), at  a purchase
price of  $45.00 per  Share (the  "Offer Price"),  net to  the seller  in  cash,
without  interest  thereon, in  accordance  with the  terms  and subject  to the
conditions set forth  in this Offer  to Purchase  and in the  related Letter  of
Transmittal  (which, as amended  from time to  time, collectively constitute the
"Offer").
 
    The Offer is being made in connection  with an Agreement and Plan of  Merger
(the  "Merger  Agreement")  dated  as  of March  29,  1996,  among  the Company,
Purchaser and Parent.  Pursuant to the  Merger Agreement, and  on the terms  and
subject  to the conditions set forth therein, Purchaser will merge with and into
the Company (the "Merger"), with the Company to be the surviving corporation  in
such  Merger, and each outstanding Share of  the Company (other than Shares held
by Parent, Purchaser or the Company, which will be cancelled, and Shares held by
stockholders who  properly exercise  appraisal rights  under Massachusetts  law)
will be converted into the right to receive an amount in cash equal to the Offer
Price.  Following the consummation  of the Merger, the  Company will continue as
the surviving corporation and  will be a wholly  owned subsidiary of Parent.  At
Purchaser's  option,  the Merger  may be  alternatively  structured so  that any
direct or indirect subsidiary of Parent is merged with and into the Company. See
Section 10. A copy of the Merger Agreement is attached as Annex I.
 
    THE BOARD OF DIRECTORS OF THE  COMPANY UNANIMOUSLY HAS DETERMINED THAT  EACH
OF  THE  OFFER AND  THE MERGER  IS  FAIR TO  AND IN  THE  BEST INTERESTS  OF THE
STOCKHOLDERS OF  THE COMPANY  AND UNANIMOUSLY  HAS APPROVED  THE OFFER  AND  THE
MERGER  AND RECOMMENDS  THAT STOCKHOLDERS  OF THE  COMPANY ACCEPT  THE OFFER AND
TENDER THEIR SHARES. SEE "RECOMMENDATION OF THE COMPANY'S BOARD OF DIRECTORS."
 
    Tendering stockholders  will  not be  obligated  to pay  brokerage  fees  or
commissions  or,  except  as  set  forth  in  Instruction  6  of  the  Letter of
Transmittal, transfer taxes on the transfer  and sale of Shares pursuant to  the
Offer.  Purchaser will pay all fees and  expenses of Goldman, Sachs & Co., which
are acting  as Dealer  Managers for  the Offer  (in such  capacity, the  "Dealer
Managers"), The First National Bank of Boston (the "Depositary") and Georgeson &
Company  Inc. (the "Information  Agent") incurred in  connection with the Offer.
See Section 16.
 
    The purpose of the  Offer is for Parent,  through Purchaser, to acquire  any
and  all outstanding Shares and to facilitate  the Merger. As of March 28, 1996,
each share of Common Stock of the Company  had a value of $30 1/4, based on  the
closing  market price  of the  Company's Shares as  reported in  THE WALL STREET
JOURNAL. The  Offer provides  an  opportunity to  existing stockholders  of  the
Company to sell Shares at a premium over recent trading prices. See Section 6.
 
    THE  OFFER  IS  CONDITIONED,  AMONG  OTHER  THINGS,  UPON  SATISFACTION,  IN
PURCHASER'S SOLE DISCRETION, OF THE  FOLLOWING CONDITIONS: (1) THAT THERE  SHALL
HAVE BEEN VALIDLY TENDERED AND NOT PROPERLY WITHDRAWN PRIOR TO THE EXPIRATION OF
THE  OFFER  A NUMBER  OF SHARES  REPRESENTING NOT  LESS THAN  A MAJORITY  OF THE
COMPANY'S OUTSTANDING  VOTING POWER  ON A  FULLY DILUTED  BASIS ON  THE DATE  OF
PURCHASE (THE "MINIMUM CONDITION"), AND (2) THE EXPIRATION OR TERMINATION OF ANY
APPLICABLE WAITING PERIOD UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT
OF  1976, AS AMENDED (THE "HSR ACT").  CERTAIN OTHER CONDITIONS TO THE OFFER ARE
DESCRIBED IN SECTION 13.
 
    As of March  28, 1996, there  were outstanding 16,792,849  shares of  Common
Stock  and 897,340 shares of Class B Common Stock. As of March 28, 1996, options
covering a total of 2,500,913 Shares were outstanding under the Company's  stock
option plans. For purposes of this Offer, "fully diluted basis" assumes that all
outstanding  stock options are  exercised and all outstanding  shares of Class B
Common Stock are converted into Common Stock.
<PAGE>
    THIS OFFER  TO PURCHASE  DOES  NOT CONSTITUTE  A  SOLICITATION OF  A  PROXY,
CONSENT OR AUTHORIZATION FOR OR WITH RESPECT TO AN ANNUAL MEETING OR ANY SPECIAL
MEETING  OF THE COMPANY'S STOCKHOLDERS  OR ANY ACTION IN  LIEU THEREOF. ANY SUCH
SOLICITATION  WILL  BE  MADE  ONLY  PURSUANT  TO  SEPARATE  PROXY  MATERIALS  IN
COMPLIANCE WITH THE REQUIREMENTS OF SECTION 14(A) OF THE SECURITIES EXCHANGE ACT
OF 1934, AS AMENDED (THE "EXCHANGE ACT").
 
                             *    *    *    *    *
 
    Purchaser  expressly reserves  the right  to waive  any one  or more  of the
conditions to  the Offer  other than  the Minimum  Condition which  may only  be
waived with the consent of the Company. See Sections 1 and 13.
 
    Stockholders are urged to read this Offer to Purchase and the related Letter
of Transmittal carefully before deciding whether to tender their Shares.
 
               RECOMMENDATION OF THE COMPANY'S BOARD OF DIRECTORS
 
    The  Board of Directors  of the Company unanimously  has determined that the
Offer and the Merger, taken together, are fair to, and in the best interests of,
the Company and  its stockholders and  unanimously has approved  the Merger  and
recommends  that the  stockholders of  the Company  accept the  Offer and tender
their Shares pursuant to the Offer. The  Offer is being effected to acquire  any
and  all outstanding Shares and to facilitate the Merger. The Board of Directors
of the Company believes that a business combination of the Company and Parent is
in the best long-term interests of  the Company and its stockholders. The  Offer
allows  stockholders to receive cash at a premium over recent trading prices for
the Company's Shares. See Sections 6 and 9.
 
    The Company's financial  advisor, Alex.  Brown &  Sons Incorporated  ("Alex.
Brown"),  has delivered  to the  Board of Directors  of the  Company its written
opinion dated  March  29,  1996 that,  as  of  such date,  and  subject  to  the
assumptions  made, matters considered and limitations set forth in such opinion,
the consideration to be received by the holders of Shares pursuant to the Merger
Agreement is fair from a financial point of view to such stockholders. A copy of
the opinion of Alex. Brown is attached as Annex II. Holders of Shares are  urged
to read such opinion carefully and in its entirety.
 
                                THE TENDER OFFER
 
1.  TERMS OF THE OFFER; EXTENSION OF TENDER PERIOD; TERMINATION; AMENDMENT
 
    Upon the terms and subject to the conditions of the Offer (including, if the
Offer  is extended or amended, the terms and conditions of any such extension or
amendment), Purchaser will  accept for payment  and pay for  all Shares  validly
tendered  and not  properly withdrawn  on or  prior to  the Expiration  Date (as
hereinafter defined) at a price of $45.00 per share, net to the seller in  cash.
The  term  "Expiration  Date"  means  12:00 Midnight,  New  York  City  time, on
Wednesday, May 1, 1996, unless Purchaser  shall have extended the period  during
which  the Offer is open,  in which event the  term "Expiration Date" shall mean
the latest time and date at which the Offer, as so extended by Purchaser,  shall
expire.
 
    The  Offer  is conditioned  upon, among  other  things, satisfaction  of the
Minimum Condition, and the expiration or termination of any waiting period under
the HSR Act. The Offer is also subject to certain other conditions set forth  in
Section   13  below.  Purchaser  expressly  reserves  the  right,  in  its  sole
discretion, to waive, in whole or in part,  any or all of the conditions of  the
Offer  (other than the  Minimum Condition, which  may not be  waived without the
prior written consent of the Company).
 
    Subject to the satisfaction of the conditions set forth in Section 13 below,
Purchaser has agreed to accept  for payment and pay  for Shares which have  been
validly  tendered  and not  withdrawn pursuant  to the  Offer as  soon as  it is
permitted to do so under applicable  law. Notwithstanding the foregoing, if  the
number  of Shares  tendered and  not withdrawn  represent less  than 90%  of the
Shares outstanding on a fully diluted  basis, Purchaser may extend the Offer  up
to  the tenth  business day following  the date  on which all  conditions to the
Offer shall first have been satisfied or waived.
 
                                       2
<PAGE>
    Purchaser expressly reserves the right, in its sole discretion, at any  time
or  from time to time, to  extend the period during which  the Offer is open for
any reason, including the non-satisfaction of any of the conditions specified in
Section 13,  by  giving  oral  or  written  notice  of  such  extension  to  the
Depositary.  During any such  extension, all Shares  previously tendered and not
properly withdrawn will remain subject to the Offer, subject to the rights of  a
tendering  stockholder to  withdraw such stockholder's  Shares. There  can be no
assurance  that  Purchaser  will  exercise  its  right  to  extend  the   Offer.
Notwithstanding  the  foregoing,  Purchaser  has  agreed  that  if  all  of  the
conditions set  forth in  Section 13  hereof are  not satisfied  on the  initial
expiration  date of the  Offer, Purchaser will extend  (and re-extend) the Offer
through June 30, 1996 to provide time to satisfy such conditions; provided, that
if Purchaser shall not have purchased Shares pursuant to the Offer prior to June
30, 1996 as the result of the receipt by the Company of an Acquisition  Proposal
(as  defined below) or as a result of a failure of the applicable waiting period
under the HSR Act to expire or the failure to obtain any necessary  governmental
or  regulatory  approvals,  Purchaser  shall extend  (and  re-extend)  the Offer
through September 30, 1996.
 
    Purchaser also  expressly reserves  the right,  subject to  applicable  laws
(including  applicable  regulations of  the  Securities and  Exchange Commission
("Commission")), in its sole discretion,  at any time or  from time to time,  to
(i)  delay acceptance for payment of or,  regardless of whether such Shares were
theretofore accepted for payment, payment for any Shares in order to comply,  in
whole  or in part, with  any applicable law, government  regulation or any other
condition contained in Sections 13 or  15, (ii) terminate the Offer (whether  or
not  any  Shares have  theretofore  been accepted  for  payment) if  any  of the
conditions referred  to  in Section  13  have not  been  satisfied or  upon  the
occurrence  of any  of the events  specified in  Section 13 and  (iii) waive any
condition or otherwise amend the  Offer in any respect;  in each case by  giving
oral  or written notice of  such delay, termination, waiver  or amendment to the
Depositary. Purchaser acknowledges that (a) Rule 14e-1(c) under the Exchange Act
requires Purchaser  to  pay  the  consideration offered  or  return  the  Shares
tendered  promptly  after the  termination or  withdrawal of  the Offer  and (b)
Purchaser may not  delay acceptance for  payment of, or  payment for (except  as
provided  by  clause  (i)  of  the  preceding  sentence),  any  Shares  upon the
occurrence of any of  the conditions specified in  Section 13 without  extending
the period of time during which the Offer is open.
 
    Any such extension, delay, termination, waiver or amendment will be followed
as promptly as practicable by public announcement thereof, and such announcement
in  the case of an extension will be made no later than 9:00 a.m., New York City
time, on the next business day  after the previously scheduled Expiration  Date.
Without  limiting the manner  in which Purchaser  may choose to  make any public
announcement, except as provided by applicable law (including Rules 14d-4(c) and
14d-6(d) under the Exchange Act, which require that material changes be promptly
disseminated to  holders  of Shares),  Purchaser  shall have  no  obligation  to
publish,  advertise or otherwise communicate any such announcement other than by
issuing a release to the Dow Jones News Service or as otherwise may be  required
by law.
 
    Purchaser may increase the Offer Price and may make any other changes in the
terms  and conditions of the Offer, provided that, unless previously approved by
the Company in writing, no change may be made that decreases the price per Share
payable in the Offer,  changes the form of  consideration payable in the  Offer,
reduces  the maximum number  of Shares to  be purchased in  the Offer or imposes
conditions to the Offer in addition to the conditions set forth in Section 13.
 
    If Purchaser  makes a  material  change in  the terms  of  the Offer  or  if
Purchaser  waives a material  condition of the Offer,  Purchaser will extend the
Offer to the extent required by Rules 14d-4(c), 14d-6(d) and 14e-1(b) under  the
Exchange  Act.  The  minimum  period  during which  an  offer  must  remain open
following material changes in  the terms of  the offer, other  than a change  in
price  or a change  in the percentage  of securities sought,  will depend on the
facts and circumstances, including the materiality, of the changes. With respect
to a  change in  price  or, subject  to certain  limitations,  a change  in  the
percentage  of securities sought, a minimum ten business day period from the day
of such change  is generally  required to  allow for  adequate dissemination  to
stockholders.  Accordingly, if prior to the Expiration Date, Purchaser decreases
the number of Shares  being sought or increases  or decreases the  consideration
offered  pursuant to the  Offer and if the  Offer is scheduled  to expire at any
time earlier than
 
                                       3
<PAGE>
the period ending on the tenth business  day from the date on which that  notice
of  such increase or decrease is first published, sent or given to stockholders,
then the  Offer will  be extended  at least  until the  expiration of  such  ten
business day period.
 
2.  ACCEPTANCE FOR PAYMENT AND PAYMENT FOR SHARES
 
    Upon the terms and subject to the conditions of the Offer (including, if the
Offer  is extended or amended, the terms and conditions of any such extension or
amendment), Purchaser  will accept  for  payment and  will  pay for  all  Shares
validly  tendered and not properly withdrawn on  or prior to the Expiration Date
as soon as practicable after the later to occur of: (i) the Expiration Date  and
(ii)  the date of satisfaction or waiver  of the conditions set forth in Section
13. In  addition, Purchaser  reserves  the right,  in  its sole  discretion  and
subject  to applicable law,  to delay acceptance  for payment of  or payment for
Shares in  order to  comply,  in whole  or in  part,  with any  applicable  law,
government  regulation or any  other condition contained  herein. See Section 13
below.
 
    For purposes of the  Offer, Purchaser shall be  deemed to have accepted  for
payment  and thereby purchased  tendered Shares of  the Company if,  as and when
Purchaser gives oral or  written notice to the  Depositary of its acceptance  of
such Shares for payment pursuant to the Offer. Payment for Shares of the Company
accepted  for payment pursuant to the Offer will be made by deposit by Purchaser
of the purchase price  to be paid  by it with  the Depositary, which  Depositary
will  act as agent for  the tendering stockholders for  the purpose of receiving
payments  from   Purchaser  and   transmitting   such  payments   to   tendering
stockholders.  Under no circumstances will interest  be paid by Purchaser on the
consideration paid  for  the  Shares  of the  Company  pursuant  to  the  Offer,
regardless  of any delay  in making such  payment. Purchaser will  pay all stock
transfer taxes,  if  any, payable  on  the transfer  of  Shares of  the  Company
purchased  by it pursuant to the Offer, except  as set forth in Instruction 6 of
the Letter of Transmittal.
 
    In all cases, payment for Shares tendered and accepted for payment  pursuant
to  the Offer will be made only after  timely receipt by the Depositary of (i) a
certificate(s) for such Shares or a timely confirmation of a book-entry transfer
of such Shares into the Depositary's account at The Depository Trust Company  or
The   Philadelphia  Depository  Trust  Company  (collectively,  the  "Book-Entry
Transfer Facilities"), (ii) a  Letter of Transmittal  (or a facsimile  thereof),
properly  completed and duly executed, with any required signature guarantees or
Agent's Message (as defined  in Section 3 below)  and (iii) any other  documents
required  by the Letter of  Transmittal. For a description  of the procedure for
tendering Shares of the Company pursuant to the Offer, see Section 3.
 
    If any tendered Shares  are not accepted  for payment for  any reason or  if
certificates  are  submitted for  more  Shares than  are  tendered, certificates
evidencing unpurchased or untendered Shares will be returned without expense  to
the  tendering stockholder  (or, in  the case  of Shares  tendered by book-entry
transfer into  the  Depositary's  account  at  a  Book-Entry  Transfer  Facility
pursuant  to the procedures set forth in Section 3, such Shares will be credited
to an account maintained  at such Book-Entry Transfer  Facility) as promptly  as
practicable following the expiration, termination or withdrawal of the Offer.
 
    If Purchaser increases the consideration offered to stockholders pursuant to
the  Offer, such increased consideration will  be paid to all stockholders whose
Shares are purchased  pursuant to  the Offer, whether  or not  such Shares  were
tendered or accepted for payment prior to such increase in consideration.
 
    Purchaser  reserves the right  to assign, in  whole or from  time to time in
part, to Parent  or a  direct or  indirect subsidiary  of Parent,  the right  to
purchase  all or any portion  of the Shares tendered  pursuant to the Offer, but
any such assignment  will not  relieve Purchaser  of its  obligations under  the
Offer  nor will any such assignment prejudice in any way the rights of tendering
stockholders to receive  payment for  Shares validly tendered  and accepted  for
payment pursuant to the Offer.
 
3.  PROCEDURE FOR TENDERING SHARES
 
    VALID  TENDER OF SHARES.  Except as set  forth below, in order for Shares to
be validly  tendered pursuant  to the  Offer, the  Letter of  Transmittal (or  a
facsimile thereof), properly completed and duly
 
                                       4
<PAGE>
executed, together with any required signature guarantees, or an Agent's Message
(as  defined  below)  in connection  with  a  book-entry delivery  of  Shares as
described below, and any other documents required by the Letter of  Transmittal,
must be received by the Depositary at one of its addresses set forth on the back
cover of this Offer to Purchase. In addition, either (i) certificates evidencing
tendered  Shares must be received by the  Depositary at any such address or such
Shares must be tendered pursuant to the procedure for book-entry transfer (and a
confirmation of receipt of such delivery must be received by the Depositary), in
each case, on or prior  to the Expiration Date  or (ii) the guaranteed  delivery
procedures  set forth  below must be  complied with. The  term "Agent's Message"
means a message transmitted by a Book-Entry Transfer Facility to and received by
the Depositary and  forming a part  of a Book-Entry  Confirmation, which  states
that  such Book-Entry Transfer  Facility has received  an express acknowledgment
from the participant in such  Book-Entry Transfer Facility tendering the  Shares
which are the subject of such Book-Entry Confirmation, that such participant has
received  and agrees to be  bound by the terms of  the Letter of Transmittal and
that Purchaser may enforce such agreement against such participant.
 
    BOOK-ENTRY TRANSFER.  The Depositary will establish an account with  respect
to  the Shares at the  Book-Entry Transfer Facilities for  purposes of the Offer
within two business days after the date of this Offer to Purchase. Any financial
institution that  is a  participant in  the system  of any  Book-Entry  Transfer
Facility may make book-entry delivery of Shares by causing a Book-Entry Transfer
Facility  to transfer  such Shares into  the Depository's  account in accordance
with that Book-Entry Transfer Facility's procedures for such transfer.  Although
delivery  of Shares may be effected  through book-entry transfer at a Book-Entry
Transfer Facility, the Letter of Transmittal (or a facsimile thereof),  properly
completed and duly executed, together with any required signature guarantees, or
an  Agent's  Message in  connection with  a book-entry  transfer, and  any other
required documents, must, in any case, be  received by the Depositary at one  of
its  addresses set forth on the back cover of this Offer to Purchase on or prior
to the Expiration Date,  or the guaranteed  delivery procedures described  below
must be complied with.
 
    DELIVERY  OF DOCUMENTS TO A BOOK-ENTRY  TRANSFER FACILITY IN ACCORDANCE WITH
SUCH BOOK-ENTRY TRANSFER FACILITY'S PROCEDURES  DOES NOT CONSTITUTE DELIVERY  TO
THE DEPOSITARY.
 
    SIGNATURE  GUARANTEES.   Except as  otherwise provided  below, signatures on
Letters of Transmittal must be guaranteed by a financial institution  (including
most  banks,  savings and  loan associations  and brokerage  houses) which  is a
participant in the Securities  Transfer Agents Medallion  Program, the New  York
Stock  Exchange  Medallion Signature  Program  or the  Stock  Exchange Medallion
Program  (each  of  the  foregoing  constituting  an  "Eligible   Institution").
Signatures on Letters of Transmittal need not be guaranteed (i) if the Letter of
Transmittal  is  signed by  the registered  holder of  Shares tendered  and such
holder has not completed either the box entitled "Special Delivery Instructions"
or the box entitled "Special Payment Instructions" on the Letter of Transmittal,
or (ii) if such Shares are tendered for the account of an Eligible  Institution.
See Instructions 1 and 5 of the Letter of Transmittal.
 
    If  the certificates  representing Shares  are registered  in the  name of a
person other than the signer of the  Letter of Transmittal, or if payment is  to
be  made or certificates for Shares not accepted for payment or not tendered are
to be returned to a person other  than the registered holder, then the  tendered
certificates  must be  endorsed or accompanied  by appropriate  stock powers, in
either case signed exactly as the name(s) of the registered holder(s)  appear(s)
on  the certificates,  with the signatures  on the certificates  or stock powers
guaranteed as  described  above. See  Instructions  1 and  5  of the  Letter  of
Transmittal.
 
    GUARANTEED  DELIVERY.  If a stockholder desires to tender Shares pursuant to
the Offer and such stockholder's certificates are not immediately available,  or
such  stockholder  cannot  deliver  the  certificates  and  all  other  required
documents to reach the Depositary  on or prior to  the Expiration Date, or  such
stockholder  cannot complete the  procedure for book-entry  transfer on a timely
basis, such  Shares may  nevertheless be  tendered if  the following  guaranteed
delivery procedures are satisfied:
 
         (i) such tender is made by or through an Eligible Institution;
 
                                       5
<PAGE>
        (ii)  a  properly  completed  and  duly  executed  Notice  of Guaranteed
    Delivery, substantially in the  form provided by  Purchaser, is received  by
    the Depositary as provided below on or prior to the Expiration Date; and
 
        (iii)   the  certificates   (or  a   book-entry  transfer  confirmation)
    representing all tendered Shares, in proper form for transfer, in each  case
    together  with the Letter  of Transmittal (or  a facsimile thereof) properly
    completed and duly executed, with any required signature guarantees (or,  in
    the  case  of  a book-entry  transfer,  an  Agent's Message)  and  any other
    documents required  by  the  Letter  of  Transmittal  are  received  by  the
    Depositary within five Nasdaq Stock Market ("Nasdaq") trading days after the
    date of execution of such Notice of Guaranteed Delivery.
 
    The Notice of Guaranteed Delivery may be delivered by hand or transmitted by
telegram,  telex,  facsimile transmission  or mail  to  the Depositary  and must
include a guarantee by  an Eligible Institution  in the form  set forth in  such
Notice of Guaranteed Delivery.
 
    THE  METHOD  OF  DELIVERY  OF  SHARE  CERTIFICATES  AND  ALL  OTHER REQUIRED
DOCUMENTS, INCLUDING DELIVERY  THROUGH ANY BOOK-ENTRY  TRANSFER FACILITY, IS  AT
THE OPTION AND RISK OF THE TENDERING STOCKHOLDER AND THE DELIVERY WILL BE DEEMED
MADE  ONLY WHEN  ACTUALLY RECEIVED  BY THE DEPOSITARY.  IF DELIVERY  IS BY MAIL,
REGISTERED MAIL WITH RETURN RECEIPT REQUESTED, PROPERLY INSURED, IS RECOMMENDED.
IN ALL CASES, SUFFICIENT TIME SHOULD BE ALLOWED TO INSURE TIMELY DELIVERY.
 
    BACKUP FEDERAL INCOME TAX WITHHOLDING.  To prevent backup federal income tax
withholding on payments made to stockholders with respect to the purchase  price
of  Shares purchased pursuant  to the Offer, each  such stockholder must provide
the Depositary with  such stockholder's correct  taxpayer identification  number
and  certify that such stockholder  is not subject to  backup federal income tax
withholding by completing  the substitute  Form W-9  included in  the Letter  of
Transmittal. See Instruction 8 of the Letter of Transmittal.
 
    APPOINTMENT  AS PROXY.   By executing  a Letter of  Transmittal, a tendering
stockholder irrevocably appoints  designees of Purchaser  as such  stockholder's
proxies  in the manner set forth in the Letter of Transmittal to the full extent
of such  stockholder's  rights with  respect  to  the Shares  tendered  by  such
stockholder  and accepted for payment by Purchaser  (and with respect to any and
all other  Shares or  other securities  issued or  issuable in  respect of  such
Shares  on or after the date of this  Offer to Purchase). All such proxies shall
be irrevocable  and  coupled with  an  interest  in the  tendered  Shares.  Such
appointment  will  be effective  when, and  only to  the extent  that, Purchaser
accepts such Shares  for payment. Upon  such acceptance for  payment, all  prior
proxies and consents granted by such stockholder with respect to such Shares and
other  securities  will be  revoked without  further  action, and  no subsequent
proxies may be given nor subsequent written consents executed (and, if given  or
executed,  such proxies or consents will not be deemed effective). The designees
of Purchaser (or any of them) will be empowered to exercise all voting and other
rights of such stockholder as they, in their sole discretion, may deem proper at
any annual,  special or  adjourned  meeting of  the Company's  stockholders,  by
written  consent or otherwise. Purchaser reserves  the right to require that, in
order for Shares  to be  deemed validly tendered,  immediately upon  Purchaser's
payment  for such Shares, Purchaser must be  able to exercise full voting rights
with respect to  such Shares, including  voting at any  meeting of  stockholders
scheduled or acting by written consent without a meeting.
 
    DETERMINATION  OF  VALIDITY.    All  questions  as  to  the  validity, form,
eligibility (including time of receipt) and acceptance for payment of any tender
of Shares  will  be  determined  by Purchaser  in  its  sole  discretion,  which
determination  shall be final and binding. Purchaser reserves the absolute right
to reject any and  all tenders of Shares  determined by it not  to be in  proper
form  or the acceptance for payment of  which may, in the opinion of Purchaser's
counsel, be unlawful. Purchaser reserves the absolute right to waive any  defect
or  irregularity  in  any  tender  of  Shares  of  any  particular  stockholder.
Purchaser's interpretation of the terms  and conditions of the Offer  (including
the  Letter  of Transmittal  and  the Instructions  thereto)  will be  final and
binding. None  of  Purchaser,  Parent,  any  of  their  affiliates  or  assigns,
 
                                       6
<PAGE>
the  Dealer Managers, the Depositary, the  Information Agent or any other person
will be under any duty to give notification of any defects or irregularities  in
tenders or incur any liability for failure to give any such notification.
 
4.  WITHDRAWAL RIGHTS
 
    Tenders  of Shares pursuant to the Offer may  be withdrawn at any time on or
prior to the Expiration Date.  Thereafter, such tenders are irrevocable,  except
that  they may be withdrawn  after June 2, 1996  unless theretofore accepted for
payment as provided in this Offer  to Purchase. If Purchaser extends the  Offer,
is  delayed in accepting for payment or paying for Shares or is unable to accept
for payment  or pay  for Shares  pursuant to  the Offer  for any  reason,  then,
without  prejudice to Purchaser's rights under the Offer, the Depositary may, on
behalf of Purchaser,  retain all  Shares tendered, and  such Shares  may not  be
withdrawn  except  to the  extent that  tendering  stockholders are  entitled to
withdrawal rights as set forth in this Section 4.
 
    For a withdrawal to be effective, a written, telegraphic, telex or facsimile
transmission notice of withdrawal must be  timely received by the Depositary  at
one  of its addresses set forth on the back cover of this Offer to Purchase. Any
notice of withdrawal must specify the name of the person who tendered the Shares
to be  withdrawn, the  number of  Shares to  be withdrawn  and the  name of  the
registered  holder,  if different  from  that of  the  person who  tendered such
Shares. If certificates evidencing Shares to be withdrawn have been delivered or
otherwise identified to the  Depositary, then prior to  the physical release  of
such  certificates,  the  serial  numbers shown  on  such  certificates  must be
submitted to the Depositary, and the signatures on the notice of withdrawal must
be guaranteed by an Eligible Institution  unless such Shares have been  tendered
for  the  account  of an  Eligible  Institution.  If Shares  have  been tendered
pursuant to the procedure  for book-entry transfer set  forth in Section 3,  the
notice  of withdrawal  must specify the  name and  number of the  account at the
Book-Entry Transfer Facility to be credited with the withdrawn Shares.
 
    Withdrawals may not be  rescinded, and Shares  withdrawn will thereafter  be
deemed not validly tendered for purposes of the Offer. However, withdrawn Shares
of  the Company may  be retendered at any  time prior to  the Expiration Date by
again following one of the procedures described in Section 3.
 
    All questions as to the form and validity (including time of receipt) of any
notice of withdrawal will  be determined by Purchaser,  in its sole  discretion,
whose  determination shall be final and  binding. None of Purchaser, Parent, any
of their  affiliates  or  assigns,  the Dealer  Managers,  the  Depositary,  the
Information  Agent  or  any  other  person  will  be  under  any  duty  to  give
notification of any  defects or irregularities  in any notice  of withdrawal  or
incur any liability for failure to give such notification.
 
5.  CERTAIN FEDERAL INCOME TAX CONSEQUENCES OF THE OFFER AND THE MERGER
 
    The  following discussion is  a summary of the  principal federal income tax
consequences of the Offer and the  Merger to holders whose Shares are  purchased
pursuant  to the  Offer or  the Merger (including  any cash  amounts received by
dissenting stockholders  pursuant  to the  exercise  of appraisal  rights).  The
discussion  applies only to holders of Shares  in whose hands Shares are capital
assets, and  may  not apply  to  Shares received  pursuant  to the  exercise  of
employee stock options or otherwise as compensation, or to holders of Shares who
are not citizens or residents of the United States.
 
    THE FEDERAL INCOME TAX CONSEQUENCES SET FORTH BELOW ARE INCLUDED FOR GENERAL
INFORMATIONAL  PURPOSES ONLY AND ARE BASED  UPON PRESENT LAW. BECAUSE INDIVIDUAL
CIRCUMSTANCES MAY  DIFFER,  EACH HOLDER  OF  SHARES  IS URGED  TO  CONSULT  SUCH
HOLDER'S  OWN TAX ADVISOR TO DETERMINE  THE APPLICABILITY OF THE RULES DISCUSSED
BELOW TO SUCH STOCKHOLDER AND  THE PARTICULAR TAX EFFECTS  OF THE OFFER AND  THE
MERGER, INCLUDING THE APPLICATION AND EFFECT OF STATE, LOCAL AND OTHER TAX LAWS.
 
    The  receipt of cash pursuant to the Offer or the Merger (including any cash
amounts  received  by  dissenting  stockholders  pursuant  to  the  exercise  of
appraisal  rights) will be a taxable transaction for federal income tax purposes
under the Internal Revenue Code of 1986  (the "Code") and also may be a  taxable
transaction under applicable state, local and other income tax laws. In general,
for  federal income tax purposes, a tendering stockholder will recognize gain or
loss equal to the difference between
 
                                       7
<PAGE>
the cash received by the stockholder pursuant to the Offer or the Merger and the
stockholder's adjusted tax basis in the  Shares tendered by the stockholder  and
purchased  pursuant to the Offer or the  Merger. Gain or loss must be determined
separately for each block of Shares (I.E., Shares acquired at the same cost in a
single transaction) tendered pursuant to the  Offer or the Merger. Such gain  or
loss  will be capital gain or loss and will be long-term gain or loss if, on the
date Purchaser  accepts the  Shares for  payment pursuant  to the  Offer or,  if
applicable, the effective date of the Merger, the Shares were held for more than
one year. There are limitations on the deductibility of capital losses.
 
    Payments  in  connection with  the Offer  or  the Merger  may be  subject to
"backup withholding" at a 31% rate. Backup withholding generally applies if  the
stockholder  fails to furnish such stockholder's social security number or other
taxpayer identification number  ("TIN"), or furnishes  an incorrect TIN.  Backup
withholding is not an additional tax but merely an advance payment, which may be
refunded  to the  extent it  results in an  overpayment of  tax. Certain persons
generally  are  exempt  from  backup  withholding,  including  corporations  and
financial  institutions. Certain penalties apply  for failure to furnish correct
information and  for  failure to  include  the reportable  payments  in  income.
Stockholders  should consult with their own tax advisors as to the qualification
for exemption from withholding and the procedure for obtaining such exemption.
 
6.  PRICE RANGE OF THE SHARES
 
    The Company's Common Stock is listed and principally traded on Nasdaq  under
the  symbol MSNS. The following table sets forth, for the periods indicated, the
high and low sale prices per share for the Common Stock as reported in THE  WALL
STREET JOURNAL for the periods indicated.
 
<TABLE>
<CAPTION>
                                                                          COMMON STOCK
                                                                    ------------------------
                                                                       HIGH          LOW
                                                                    -----------  -----------
<S>                                                                 <C>          <C>
Fiscal 1995:
  First Quarter (from June 30, 1994)..............................  $      121/4 $      12
  Second Quarter..................................................         203/8        12
  Third Quarter...................................................         26           163/4
  Fourth Quarter..................................................         251/8        185/8
Fiscal 1996:
  First Quarter...................................................         20           137/8
  Second Quarter..................................................         271/4        17
  Third Quarter...................................................         32           197/8
  Fourth Quarter..................................................         461/2        24
</TABLE>
 
    On  March 28, 1996, the  last full trading day  prior to announcement of the
execution of  the Merger  Agreement and  Purchaser's intention  to commence  the
Offer,  the closing  sale price of  the Common Stock  on Nasdaq was  $30 1/4 per
share of Common Stock. On April 3, 1996, the last full trading day prior to  the
commencement  of the  Offer, such  closing sales  price was  $44 1/2  per share.
STOCKHOLDERS ARE URGED TO OBTAIN A CURRENT MARKET QUOTATION FOR THE SHARES.
 
7.  CERTAIN INFORMATION CONCERNING THE COMPANY
 
    GENERAL.   The Company  is a  Massachusetts corporation  with its  principal
offices  currently  located at  266 Second  Avenue, Waltham,  Massachusetts. The
Company develops, manufactures and markets self-testing blood glucose monitoring
systems  that  enable  people  with  diabetes  to  manage  their  disease   more
effectively.
 
    FINANCIAL  INFORMATION.   Set forth  below is  certain selected consolidated
financial information with  respect to  the Company and  its subsidiaries.  More
comprehensive  financial information is included  in reports and other documents
filed by the Company with the Commission, and the following summary is qualified
in its entirety by reference to such reports and other documents and all of  the
financial
 
                                       8
<PAGE>
information  (including any related  notes) contained therein.  Such reports and
other documents are available for  inspection and copies thereof are  obtainable
in the manner set forth below under "Available Information."
 
                                MEDISENSE, INC.
                   SUMMARY CONSOLIDATED FINANCIAL INFORMATION
 
<TABLE>
<CAPTION>
                                                                NINE MONTHS ENDED
                                                                DECEMBER 31, 1995
                                                               -------------------
                                                                                           FISCAL YEAR ENDED
                                                                                               MARCH 31,
                                                                                    -------------------------------
                                                                                      1995       1994       1993
                                                                                    ---------  ---------  ---------
                                                                   (DOLLARS IN MILLIONS EXCEPT PER SHARE DATA)
<S>                                                            <C>                  <C>        <C>        <C>
STATEMENT OF INCOME DATA:
Net Revenue..................................................       $   129.7       $   141.0  $   110.4  $    93.2
Income (Loss) Before Extraordinary Items.....................            22.5            22.0        6.2       (2.5)
Net Income (Loss)............................................            22.5            22.0        6.2       (2.5)
PER SHARE DATA:
Net Income Per Common Share..................................       $    1.21       $    1.34  $    0.61  $     N/A
Net Income Per Share on a Fully Diluted Basis................            1.21            1.34       0.61        N/A
BALANCE SHEET DATA:
Working Capital (Deficiency).................................       $    56.0       $    37.0  $     8.6  $    (1.7)
Total Assets.................................................           110.3            82.0       43.5       45.6
Total Indebtedness...........................................            36.3            33.2       74.8       83.4
Shareholders' Equity (Deficit)...............................            73.9            48.8      (31.3)     (37.8)
Average Number of Common Shares Outstanding
 (in thousands)..............................................          18,575          16,349     15,684        N/A
</TABLE>
 
    AVAILABLE  INFORMATION.  The  Company is registered  under the Exchange Act,
and, accordingly, is  subject to  the informational filing  requirements of  the
Exchange  Act. In accordance therewith the Company files periodic reports, proxy
statements and  other information  with the  Commission under  the Exchange  Act
relating  to its business, financial condition and other matters. The Company is
required to  disclose  in  such  proxy statements  certain  information,  as  of
particular  dates,  concerning  the  Company's  directors  and  officers,  their
remuneration, stock  options  granted to  them,  the principal  holders  of  the
Company's  securities and any material interest  of such persons in transactions
with the Company. Such  reports, proxy statements and  other information may  be
inspected at the Commission's office at 450 Fifth Street, N.W., Washington, D.C.
20549,  and also should be available for  inspection and copying at the regional
offices of  the Commission  located  at 500  West  Madison Street,  Suite  1400,
Chicago,  Illinois 60661-2511; and  7 World Trade Center,  13th Floor, New York,
New York 10048. Copies may be obtained by mail from the Public Reference Section
of the Commission, 450 Fifth Street, N.W., Washington, D.C. 20549, at prescribed
rates. In addition, such material should also be available for inspection at the
library of Nasdaq.
 
8.  CERTAIN INFORMATION CONCERNING PURCHASER AND PARENT
 
    GENERAL.  Purchaser, a Massachusetts corporation and wholly owned subsidiary
of Parent, recently was organized for the purpose of effecting the Offer and the
Merger and has not carried on any activities except in connection with the Offer
and the Merger. The principal executive offices of Purchaser are located at  100
Abbott  Park Road, Abbott  Park, Illinois. All the  outstanding capital stock of
Purchaser is owned by Parent.
 
    Parent is an Illinois corporation with its principal offices located at  100
Abbott  Park Road,  Abbott Park,  Illinois. Parent's  principal business  is the
discovery, development, manufacture and sale of a broad and diversified line  of
health  care products and  services. Parent is  a public company  whose stock is
traded on the New York Stock Exchange, Chicago Stock Exchange and Pacific  Stock
Exchange.
 
                                       9
<PAGE>
    FINANCIAL  INFORMATION.   Set forth  below is  certain selected consolidated
financial information with  respect to  Parent and  its subsidiaries  as of  its
fiscal  years  ended  December  31,  1993,  1994  and  1995.  More comprehensive
financial information is included  in reports and in  documents filed by  Parent
with  the Commission, and the following summary  is qualified in its entirety by
reference to  such  reports  and  other  documents  and  all  of  the  financial
information  (including any related  notes) contained therein.  Such reports and
other documents should be available for inspection and copies thereof should  be
obtainable in the manner set forth below under "Available Information."
 
                      ABBOTT LABORATORIES AND SUBSIDIARIES
                   SUMMARY CONSOLIDATED FINANCIAL INFORMATION
 
<TABLE>
<CAPTION>
                                                                              FISCAL YEARS ENDED DECEMBER 31,
                                                                           -------------------------------------
                                                                              1995         1994         1993
                                                                           -----------  -----------  -----------
                                                                                (DOLLARS IN MILLIONS EXCEPT
                                                                                      PER SHARE DATA)
<S>                                                                        <C>          <C>          <C>
STATEMENT OF EARNINGS DATA:
Net Sales................................................................  $  10,012.2  $   9,156.0  $   8,407.8
Earnings Before Extraordinary Items......................................      1,688.7      1,516.7      1,399.1
Net Earnings.............................................................      1,688.8      1,516.7      1,399.1
PER SHARE DATA:
Net Earnings Per Common Share............................................  $      2.12  $      1.87  $      1.69
Net earnings Per Share on a Fully Diluted Basis..........................         2.10         1.85         1.67
BALANCE SHEET DATA:
Working Capital..........................................................  $     436.4  $     400.5  $     490.6
Total Assets.............................................................      9,412.6      8,523.7      7,688.6
Total Assets Less Goodwill...............................................      9,256.6      8,412.2      7,561.8
Total Indebtedness.......................................................      5,015.7      4,474.3      4,013.6
Shareholders' Equity.....................................................      4,396.8      4,049.4      3,674.9
Average Number of Common Shares Outstanding (in thousands)...............      795,362      812,236      828,988
</TABLE>
 
    AVAILABLE  INFORMATION.  Parent  is registered under  the Exchange Act, and,
accordingly, is subject to the informational filing requirements of the Exchange
Act. In accordance  therewith, Parent files  periodic reports, proxy  statements
and other information with the Commission under the Exchange Act relating to its
business,  financial condition and other matters. Parent is required to disclose
in such proxy statements certain information, as of particular dates, concerning
Parent's directors and  officers, their remuneration,  stock options granted  to
them,  the principal holders of Parent's securities and any material interest of
such persons in  transactions with  Parent. Such reports,  proxy statements  and
other  information  may be  inspected at  the Commission's  office at  450 Fifth
Street,  N.W.,  Washington,  D.C.  20549,  and  also  should  be  available  for
inspection  and copying at the regional offices of the Commission located at 500
West Madison Street, Suite 1400, Chicago, Illinois 60661-2511; and 7 World Trade
Center, 13th Floor, New  York, New York  10048. Copies may  be obtained by  mail
from  the Public  Reference Section of  the Commission, 450  Fifth Street, N.W.,
Washington, D.C. 20549, at prescribed rates.
 
    Except as described  in this  Offer to Purchase,  (i) none  of Purchaser  or
Parent  or, to  the best knowledge  of Purchaser  or Parent, any  of the persons
listed in Schedule I or any associate  or majority owned subsidiary of any  such
persons,  beneficially owns or has a right to acquire any equity security of the
Company and  (ii) none  of Purchaser  or Parent  or, to  the best  knowledge  of
Purchaser  or Parent, any of the other persons  referred to above, or any of the
respective  directors,  executive  officers  or  subsidiaries  of  any  of   the
foregoing,  has effected any  transaction in any equity  security of the Company
during the past 60 days.
 
    Except as described in this Offer to Purchase, (i) none of Purchaser, Parent
or, to the best knowledge of Purchaser  or Parent, any of the persons listed  in
Schedule I has any contract, arrangement, understanding or relationship (whether
or   not  legally   enforceable)  with   any  other   person  with   respect  to
 
                                       10
<PAGE>
any securities of  the Company,  including, but  not limited  to, any  contract,
arrangement, understanding or relationship concerning the transfer of the voting
of  any such  securities, joint ventures,  loan or option  arrangements, puts or
calls,  guarantees  of  loans,  guarantees  against  loss,  or  the  giving   or
withholding  of  proxies;  (ii) there  have  been no  contacts,  negotiations or
transactions between Purchaser, Parent or  any of their respective  subsidiaries
or,  to the best knowledge of Purchaser or  Parent, any of the persons listed on
Schedule I on the one hand, and the Company or any of its directors, officers or
affiliates,  on  the   other  hand,  concerning   a  merger,  consolidation   or
acquisition,  tender  offer  or  other acquisition  of  securities,  election of
directors, a sale or other transfer of a material amount of assets or concerning
any other  transactions with  the  Company that  are  required to  be  disclosed
pursuant to the rules and regulations of the Commission.
 
9.  BACKGROUND OF THE MERGER AND THE OFFER
 
    On  February 15,  1996, Miles  D. White,  Senior Vice  President, Diagnostic
Operations of  Parent  and Robert  L.  Coleman, President  and  Chief  Executive
Officer  of  the Company  met  and discussed,  in  general terms,  the Company's
business and prospects  and the  possibility of a  business combination  between
Parent and the Company.
 
    On  February 27,  1996, Dr.  Coleman, Richard  C.E. Morgan,  Chairman of the
Board of Directors of the Company and James R. Tobin, a Director of the Company,
met with Mr. White,  Duane L. Burnham, Chairman  and Chief Executive Officer  of
Parent,  Thomas R. Hodgson, President and  Chief Operating Officer of Parent and
Gary P. Coughlan, Senior Vice President, Finance and Chief Financial Officer  of
Parent,  to discuss further the business of the Company and the possibility that
Parent might acquire the Company.
 
    On March 2, 1996, the Company's  Board of Directors met via  teleconference.
At  this  meeting, Mr.  Morgan and  Dr.  Coleman summarized  to the  Board their
conversations with the representatives  of Parent. The  Company's Board and  the
Company's legal and financial advisors discussed these conversations, as well as
the  advisability of the Company's entering  into a business combination at that
time compared  to  remaining  independent.  The  Board  and  its  advisors  also
discussed  the likelihood that there would  be other interested parties, as well
as possible  antitrust and  other issues  with respect  to potential  interested
parties.  Following  these  discussions,  the  Board  authorized  the  Company's
management to  enter into  a confidentiality  agreement with  Parent  containing
"standstill"   provisions   prohibiting   certain   unsolicited   proposals  and
transactions and to commence discussions of a possible business combination with
Parent.
 
    Following the Company's March 2, 1996 Board meeting, the Company and  Parent
began  to discuss  a confidentiality and  standstill agreement. From  March 2 to
March 13, 1996, representatives of Parent  and the Company and their  respective
financial  and legal advisors exchanged  drafts and discussed various provisions
of a confidentiality and standstill agreement.
 
    On March 13,  1996, the Company  and Parent entered  into a  confidentiality
agreement   (the   "Confidentiality   Agreement")  providing   for   the  mutual
non-disclosure of confidential information exchanged by the Company and  Parent.
The Confidentiality Agreement also provided for a one year standstill by Parent,
subject  to certain  exceptions, and  a 16-day  period during  which the Company
would negotiate exclusively with Parent. Immediately thereafter, representatives
of Alex. Brown, financial advisors to  the Company, met with representatives  of
Goldman,  Sachs &  Co., financial advisors  to Parent, to  discuss the financial
advisors' respective views as to the methodologies that should be used to  value
the Company.
 
    Later  on  March 13,  1996,  Mr. Burnham  telephoned  Mr. Morgan  to discuss
certain financial  aspects  of the  proposed  transaction. On  March  15,  1996,
representatives  of Alex. Brown  and Goldman, Sachs  & Co. met  again to discuss
valuation methodologies. From March  13, 1996 through  March 29, 1996,  Parent's
financial  and legal advisors continued to  request and review various documents
containing confidential information supplied by the Company and discuss  various
due diligence matters.
 
                                       11
<PAGE>
    On March 18, 1996, Mr. White and certain other representatives of Parent and
Parent's   financial   advisors  met   with  Dr.   Coleman  and   certain  other
representatives of the  Company and  the Company's financial  advisors. At  that
meeting,  representatives  of  the  Company  made  a  financial  presentation to
Parent's representatives and financial advisors and discussed various aspects of
the Company's  business.  Tentative discussions  of  a possible  purchase  price
indicated that the views of the Company and Parent were significantly different.
From  March  18, 1996  through March  25, 1996,  the parties  exchanged numerous
telephone calls with respect to valuation and other matters.
 
    On March 25, 1996,  Mr. Burnham and  Mr. White met with  Mr. Morgan and  Dr.
Coleman  to discuss  the terms  of a possible  transaction. At  that meeting Mr.
Burnham and Mr.  Morgan, after extensive  discussion, established a  preliminary
basis,  subject to satisfactory  completion of Parent's  due diligence review of
the Company,  negotiation  of satisfactory  terms  of a  merger  agreement,  the
receipt  of  fairness opinions  and  the approval  of  the respective  Boards of
Directors of  Parent  and the  Company,  to continue  discussions  regarding  an
acquisition  of the  Company by  Parent at  a price  of $45.00  per Share, which
represented a compromise between the competing views as to the price.
 
    On March 26,  1996, the Company's  Board of Directors  at a regular  meeting
discussed  the proposed  transaction, and  received the  views of  the Company's
financial and legal advisors. At  the meeting, the Board received  presentations
from  management and the  Company's financial and  legal advisors. The Company's
management reviewed  the state  of  the Company's  business and  its  prospects.
Shearman  &  Sterling,  the  Company's  special  counsel,  reviewed  the Board's
fiduciary duties to the Company and its stockholders, and Alex. Brown  presented
its  analysis as to the  proposed consideration to be  received by the Company's
stockholders.  Following  the  presentations,  the  Board,  management  and  the
Company's  advisors discussed the merits  and risks of alternative transactions.
The Board  again discussed  the number  of likely  alternative bidders  and  the
antitrust  and other risks that would impact the likelihood of consummation of a
transaction with such other bidders. During this meeting, special counsel to the
Company contacted counsel to Parent by telephone to discuss certain aspects of a
possible agreement relating to the proposed transaction.
 
    On March 26, 1996, counsel for Parent distributed a draft Agreement and Plan
of Merger to the Company and its  legal and financial advisors. On March 26  and
27,  1996, representatives of Parent met  with representatives of the Company to
discuss certain additional due diligence matters and request certain  additional
information.  Also on March 27, 1996, the Company's legal advisors distributed a
revised draft Agreement and Plan of Merger to Parent and its legal and financial
advisors.
 
    On March 28, 1996, a representative  of the Company and the Company's  legal
advisors  met  with representatives  of Parent  and  Parent's legal  advisors to
continue negotiation of the terms of the proposed Agreement and Plan of  Merger.
On  March 28,  1996, Parent's financial  advisors held  discussions by telephone
with the Company's financial advisors regarding certain financial aspects of the
proposed transaction.
 
    On the morning of March 29, 1996, after completion of the negotiations  over
the proposed Agreement and Plan of Merger, the Board of Directors of the Company
held  a  special  meeting  by  teleconference to  review,  with  the  advice and
assistance of the Company's financial and legal advisors, the proposed Agreement
and Plan  of Merger  and the  transactions contemplated  thereby, including  the
Offer  and the Merger. At the meeting, counsel to the Company reviewed the terms
of the  Merger Agreement.  Alex.  Brown presented  an  update of  its  financial
analysis   and  rendered  to  the  Board  its  written  opinion  that  the  cash
consideration of  $45.00 per  Share to  be  received by  holders of  the  Shares
pursuant  to the Merger Agreement is fair from a financial point of view to such
stockholders. Following a  number of  questions from, and  discussion among  the
directors,  the Company's Board of Directors unanimously (i) approved the Merger
Agreement and the transactions contemplated thereby and authorized the execution
and delivery  thereof, (ii)  determined that  the Offer  and the  Merger,  taken
together,  are  fair to,  and  in the  best interests  of,  the Company  and its
stockholders, and (iii) recommended that  the Company's stockholders accept  the
Offer and tender their Shares to Purchaser.
 
                                       12
<PAGE>
    Simultaneously  with the special meeting of the Company's Board of Directors
on March 29, 1996, the  Board of Directors of Parent  held a special meeting  to
review, with the advice and assistance of Parent's financial and legal advisors,
the  proposed Agreement  and Plan  of Merger  and the  transactions contemplated
thereby,  including  the  Offer  and  the  Merger.  At  such  meeting,  Parent's
management,  financial  advisors and  legal advisors  made presentations  to the
Board concerning the transaction and Parent's financial advisor, Goldman,  Sachs
&  Co., provided its written opinion to  the effect that the consideration to be
paid by Parent pursuant to the Merger  Agreement is fair to the stockholders  of
Parent  from a financial point of view. Following the Board of Directors' review
of the transaction, Parent's Board of Directors unanimously approved the  Merger
Agreement   and  the  transactions  contemplated  thereby,  and  authorized  the
execution and delivery thereof.
 
    Also on March  29, 1996, immediately  after the respective  meetings of  the
Boards  of Directors of the Company and  Parent had concluded, the Agreement and
Plan of Merger was executed and  delivered by the Company, Parent and  Purchaser
and the Company and Parent issued the following joint press release:
 
    ABBOTT LABORATORIES TO ACQUIRE MEDISENSE, INC.
 
        Abbott   Park,  Ill.,  and  Waltham,  Ma.,  March  29,  1996  --  Abbott
    Laboratories (NYSE: ABT) and MediSense, Inc. (NASDAQ: MSNS) today  announced
    that  they  have signed  a definitive  agreement  through which  Abbott will
    acquire  MediSense,  the  biosensor  technology  leader  in  blood   glucose
    self-testing systems for people with diabetes.
 
        Under  the terms of  the agreement, Abbott  will make a  tender offer to
    acquire 100  percent of  the outstanding  shares of  MediSense for  $45  per
    share,  or an  equity value  of approximately  $876 million.  The Abbott and
    MediSense boards of directors have endorsed  the offer. The tender offer  is
    expected  to be completed in approximately five weeks, subject to regulatory
    approvals and  customary closing  conditions.  Following the  tender  offer,
    MediSense   will  be  merged  into   a  wholly-owned  subsidiary  of  Abbott
    Laboratories, and each remaining MediSense shareholder will receive $45  per
    share in exchange for each MediSense share held.
 
        "We  are extremely  pleased to  add MediSense's  superior technology and
    outstanding people  to our  company," said  Duane L.  Burnham, chairman  and
    chief  executive officer of  Abbott Laboratories. "MediSense  fits very well
    with our  diagnostics operations,  and will  create many  opportunities  for
    synergy with our other divisions as well."
 
        According   to  Miles  D.  White,  senior  vice  president,  diagnostics
    operations, the  acquisition  advances  Abbott's interests  in  the  glucose
    monitoring  market.  "This  important strategic  step,  combined  with other
    internal and external initiatives  to secure industry-leading technology  in
    glucose  monitoring, will position Abbott very  favorably in this market. In
    addition to providing immediate access to the fastest-growing segment of the
    diagnostics  market,  MediSense's  research  and  development  program  will
    augment  our existing work to  develop and commercialize future non-invasive
    monitoring technologies," said White.
 
        "We are delighted to  become a part of  the world's leading  diagnostics
    company,"  said  Robert L.  Coleman,  Ph.D., president  and  chief executive
    officer of  MediSense.  "The  combination  of  the  two  organizations  will
    accelerate   market  growth  and  will   ensure  continued  development  and
    availability of therapies to improve the care of people with diabetes."
 
        MediSense manufactures  products  that  allow people  with  diabetes  to
    routinely  measure blood glucose  which is critical  to diabetes management.
    The products are  compact, easy-to-use  home glucose  meters and  disposable
    single-use  test  strips.  MediSense  was the  first  company  to  develop a
    biosensor-based  blood  glucose  self-testing  system.  MediSense's  leading
    system, the Precision Q-I-D-TM-, provides accurate results, with less blood,
    faster than any competing product.
 
                                       13
<PAGE>
        The  MediSense  subsidiary  of Abbott  will  continue to  be  located in
    Massachusetts, with Dr.  Coleman remaining as  president of the  subsidiary.
    MediSense  is  a worldwide  developer,  manufacturer and  marketer  of blood
    glucose self-testing  systems that  enable people  with diabetes  to  manage
    their  disease  more  effectively. MediSense  believes  the  convenience and
    simplicity  of  its  products   promote  increased  testing  compliance   by
    individuals with diabetes and provide for more effective management of their
    condition.
 
        Abbott  Laboratories is a diversified global manufacturer of health care
    products, employing  50,000 people.  The  company researches,  develops  and
    markets  pharmaceutical, diagnostic,  nutritional and  hospital products. In
    1995, the  company's sales  and net  earnings were  $10.0 billion  and  $1.7
    billion, respectively, with earnings per share of $2.12.
 
                                                    * * *
 
    The Purchaser commenced the Offer on April 4, 1996.
 
10.  PURPOSE OF THE OFFER; THE MERGER AGREEMENT
 
    PURPOSE OF THE OFFER
 
    The purpose of the Offer is to acquire any and all outstanding Shares and to
facilitate  the Merger, which the Board of  Directors of the Company believes is
in the best interest of the  Company's stockholders. The Offer also provides  an
opportunity  to  existing stockholders  of  the Company  to  sell Shares  of the
Company at a premium over recent trading prices. See Section 6.
 
    THE AGREEMENT AND PLAN OF MERGER
 
    The following  is  a brief  summary  of  certain provisions  of  the  Merger
Agreement,  a copy of which is attached as Annex I to this Offer to Purchase and
is incorporated  herein  by reference.  This  summary  does not  purport  to  be
complete  and is qualified in its entirety by reference to the Merger Agreement.
ALL STOCKHOLDERS OF THE COMPANY  ARE URGED TO READ  THE MERGER AGREEMENT IN  ITS
ENTIRETY.  Capitalized terms not  defined herein have the  meanings set forth in
the Merger Agreement.
 
THE MERGER
 
    The Merger Agreement provides that, at the Effective Time (as defined below)
and upon the terms  and subject to  the conditions of  the Merger Agreement  and
Massachusetts  law, Purchaser will be merged with  and into the Company, and the
separate existence of Purchaser  will cease with the  Company continuing as  the
surviving  corporation. At Purchaser's  option, the Merger  may be structured so
that any direct or  indirect subsidiary of  Parent is merged  with and into  the
Company.
 
    As soon as practicable after the satisfaction or waiver of the conditions to
the  Merger, the  parties will  file with the  Secretary of  the Commonwealth of
Massachusetts the  articles  of  merger  and will  make  all  other  filings  or
recordings  required by Massachusetts law. The Merger will become effective upon
the filing and acceptance of the articles of merger, or at such later time as is
specified in the articles of merger (the "Effective Time").
 
    At the  Effective Time,  each  Share outstanding  immediately prior  to  the
Effective  Time (other  than Shares held  by Parent, Purchaser,  the Company and
Shares held  by  stockholders  who  properly  exercise  appraisal  rights  under
Massachusetts  law), will  be cancelled and  extinguished and  will be converted
into the  right to  receive an  amount equal  to the  Offer Price  (the  "Merger
Consideration").
 
    Shares  outstanding immediately  prior to the  Effective Time and  held by a
holder who has not voted in favor of the Merger or consented thereto in  writing
and  who has demanded appraisal for such Shares in accordance with Massachusetts
law will  not be  converted into  a right  to receive  the Merger  Consideration
unless  such  holder  fails to  perfect  or  withdraws or  otherwise  loses such
holder's right to appraisal. If, after the Effective Time, such holder fails  to
perfect or withdraws or loses such holder's right to appraisal, such Shares will
be  treated as  if they had  been converted into  a right to  receive the Merger
Consideration without interest thereon.
 
                                       14
<PAGE>
    The  Merger  Agreement   provides  that,  if   approval  by  the   Company's
stockholders is required by applicable law to consummate the Merger, the Company
will,  as soon as practicable  following the consummation of  the Offer, hold an
annual or special meeting of its  stockholders to consider and take action  upon
the Merger Agreement, including in the proxy statement the recommendation of the
Board  of  Directors of  the  Company that  stockholders  vote in  favor  of the
approval of adoption of the  Merger Agreement and the transactions  contemplated
thereby.  At such meeting,  Parent and Purchaser  will vote all  Shares owned by
them in favor of the Merger Agreement and the transactions contemplated thereby.
 
    Promptly after the Effective  Time, the surviving  corporation will mail  to
each  record holder, as of  the Effective Time, a  certificate(s) that, prior to
the Effective Time, represented Shares, along  with a letter of transmittal  and
instructions  for effecting  the surrender of  such certificates  for the Merger
Consideration. Upon  surrender of  the  certificate(s) representing  a  holder's
Shares,  together with a  completed and validly  executed letter of transmittal,
such holder will  be entitled  to receive  the Merger  Consideration in  respect
thereof. Until so surrendered or exchanged, each certificate will represent only
the right to receive the Merger Consideration.
 
THE OFFER
 
    Pursuant  to the  terms of the  Merger Agreement, Purchaser  was required to
commence the Offer  no later than  the fifth business  day following the  public
announcement  of the terms of the  Merger Agreement. The obligation of Purchaser
to accept for payment and pay for  any Shares tendered pursuant to the Offer  is
subject only to the Offer Conditions. Purchaser may increase the Offer Price and
may  make any other changes  in the terms and  conditions of the Offer, provided
that, unless previously  approved by the  Company in writing,  no change may  be
made  that decreases the price per Share  payable in the Offer, changes the form
of consideration payable in the Offer,  reduces the maximum number of Shares  to
be  purchased in the Offer or imposes conditions to the Offer in addition to the
conditions set forth in Section 13.
 
    Subject to the satisfaction of the conditions set forth in Section 13 below,
Purchaser has agreed to accept  for payment and pay  for Shares which have  been
validly  tendered  and not  withdrawn pursuant  to the  Offer as  soon as  it is
permitted to do so under applicable  law. Notwithstanding the foregoing, if  the
number  of Shares  tendered and  not withdrawn  represent less  than 90%  of the
Shares outstanding on a fully diluted  basis, Purchaser may extend the Offer  up
to  the tenth  business day following  the date  on which all  conditions to the
Offer shall first have been satisfied or waived.
 
    The Merger Agreement provides that if the Offer Conditions are not satisfied
on the  initial  expiration date  of  the  Offer, Purchaser  shall  extend  (and
re-extend)  the Offer  through June  30, 1996  to provide  time to  satisfy such
conditions; provided that, if Purchaser has not purchased Shares pursuant to the
Offer prior to June 30, 1996 as the  result of the receipt by the Company of  an
Acquisition  Proposal (as  defined below)  or as  a result  of a  failure of the
applicable waiting period under the HSR Act  to expire or the failure to  obtain
any  necessary governmental or regulatory approvals, Purchaser shall extend (and
re-extend) the Offer through September 30, 1996.
 
    The Merger  Agreement  requires, as  soon  as  practicable on  the  date  of
commencement  of the Offer, (a) Parent and Purchaser to file with the Commission
a Tender Offer Statement on Schedule 14D-1 with respect to the Offer which  will
contain  the offer to purchase and form of the related letter of transmittal and
(b) the  Company  to  file with  the  Commission  a  Solicitation/Recommendation
Statement  on Schedule 14D-9  which it will mail  to stockholders promptly after
the commencement of the Offer. Purchaser and the Company also agreed to take all
steps necessary to cause the offer to purchase and form of the related letter of
transmittal to  be  disseminated to  holders  of Shares  as  and to  the  extent
required by applicable federal securities laws.
 
BOARD REPRESENTATION
 
    Promptly  upon the purchase by Purchaser of Shares pursuant to the Offer and
from time to time thereafter, Purchaser  will be entitled to designate a  number
of directors on the Company's Board of Directors equal to the product of (i) the
total    number   of   directors   on   the   Company's   Board   of   Directors
 
                                       15
<PAGE>
and (ii)  Purchaser's percentage  ownership  of the  outstanding Shares  of  the
Company.  The Company will  either increase the  size of the  Company's Board of
Directors or secure  the resignation  of the  necessary number  of directors  to
enable  Purchaser's designees to be elected to the Company's Board of Directors,
and will cause such designees to be elected to the Company's Board of Directors.
 
    Following  the  election  or  appointment  of  Purchaser's  designees,   any
amendment  of the Merger  Agreement or the Restated  Articles of Organization or
By-laws of the Company, any termination of the Merger Agreement by the  Company,
and  any extension by the Company of  the time for performance of obligations or
the waiver of any rights under the  Merger Agreement will require the vote of  a
majority  of  directors of  the  Company who  are  not Purchaser's  designees or
employees of the Company.
 
REPRESENTATIONS AND WARRANTIES
 
    The Merger Agreement contains various representations and warranties of  the
Company,  including  representations by  the  Company as  to:  (i) organization,
qualification and similar corporate matters of the Company and its subsidiaries,
(ii)  capitalization   of  the   Company  and   its  subsidiaries,   (iii)   the
authorization, execution, delivery, performance and enforceability of the Merger
Agreement,  (iv)  the  non-contravention  of the  Merger  Agreement  and related
transactions with any charter provision,  by-law, material contract, order,  law
or regulation to which the Company or its subsidiaries is a party or by which it
is  bound or obligated,  (v) the filing  of required Commission  reports and the
absence of untrue statements of material facts or omissions of material facts in
such reports, (vi) the absence  of changes or events  which have had a  material
adverse  effect on the Company and the absence of certain derivative instruments
that would result in a material adverse effect on the Company, (vii) the absence
of untrue statements  of material facts  or omissions of  material facts in  the
Schedule  14D-9 and the proxy  statement to be sent  to stockholders, (viii) the
absence of payments to any intermediary  other than Alex. Brown of any  finder's
or  other fee or commission,  (ix) claims and litigation,  (x) the filing of tax
returns and  the  payment  of  taxes,  (xi)  employee  benefits  matters,  (xii)
compliance  with laws, rules,  statutes, orders, ordinances  or regulations, and
material notes,  bonds, mortgages,  indentures, contracts,  agreements,  leases,
licenses,  permits, franchise or other instruments or obligations of the Company
or any of  its subsidiaries  which would result  in a  material adverse  effect,
(xiii) the absence of environmental claims and compliance with all environmental
laws  and regulations, (xiv) possession of  all necessary rights and licenses in
intellectual property, (xv)  possession of  all necessary  insurance, (xvi)  the
absence  of real property ownership and the possession and enforceability of all
real property leases, (xvii) the absence  of notices, citations or decisions  of
governmental  or regulatory bodies and recalls  or warning letters from the Food
and Drug  Administration with  respect to  any product  produced,  manufactured,
marketed  or distributed by  the Company, and possession  of and compliance with
all necessary approvals, clearances, authorizations, licenses and  registrations
relating  to  such  products,  (xviii) labor  matters,  (xix)  applicable voting
requirements and (xx) inapplicability of state takeover laws.
 
    The  Merger  Agreement  contains   various  customary  representations   and
warranties  of  Parent and  Purchaser, including  representations by  Parent and
Purchaser as to: (i) organization,  qualification and similar corporate  matters
of   Parent  and   Purchaser,  (ii)  the   authorization,  execution,  delivery,
performance  and   enforceability   of   the   Merger   Agreement,   (iii)   the
non-contravention  of  the Merger  Agreement and  related transactions  with any
charter provision, by-law, material contract, order, law or regulation to  which
Parent  or Purchaser is a party  or by which it is  bound or obligated, (iv) the
absence of untrue statements of material facts or omissions of material facts in
any documents related to the Offer and in information provided to the Company in
connection with the Schedule 14D-1 and proxy statement, (v) the absence of prior
activities of Purchaser other than in connection with or as contemplated by  the
Merger  Agreement  and (vi)  the possession  of all  funds necessary  to satisfy
Purchaser's obligations under the Merger Agreement.
 
COVENANTS
 
    CONDUCT OF BUSINESS OF THE COMPANY.   From the date of the Merger  Agreement
to  the time Purchaser's designees are elected  as directors of the Company, the
Company and its subsidiaries will each
 
                                       16
<PAGE>
conduct its operations in the ordinary  course of business consistent with  past
practice, and the Company and its subsidiaries will each use its reasonable best
efforts  to preserve  intact its  business organization,  to keep  available the
services of its officers  and employees and  to maintain existing  relationships
with  licensors, licensees, suppliers,  contractors, distributors, customers and
others having business relationships with it.
 
    Accordingly, prior  to the  date  Purchaser's nominees  are elected  to  the
Company's  Board of Directors,  neither the Company nor  any of its subsidiaries
may, without prior written consent of Purchaser, engage or agree to engage in an
enumerated list of  transactions generally  characterized as  being outside  the
ordinary  course of business. Transactions  requiring Purchaser's prior approval
include actions by the Company or its subsidiaries to (i) amend its articles  of
organization  or  by-laws  or increase  or  propose  to increase  the  number of
directors; (ii) authorize for issuance, issue, sell, deliver or agree to  commit
to  issue, sell  or deliver any  stock of any  class or any  other securities or
equity equivalents (including, without  limitation, stock appreciation  rights),
except  as required by option agreements and option plans as in effect as of the
date of the Merger Agreement, or amend  any of the terms of any such  securities
or  agreements outstanding as of the date  of the Merger Agreement; (iii) split,
combine or reclassify any shares of its capital stock, declare, set aside or pay
any dividend or other distribution (whether  in cash, stock, or property or  any
combination  thereof) in respect of its  capital stock, or redeem, repurchase or
otherwise acquire any of its securities  or any securities of its  subsidiaries;
(iv) incur any debt or issue any debt securities or assume, guarantee or endorse
the  obligations  of  any other  person,  make  any loans,  advances  or capital
contributions to, or  investments in,  any other  person (other  than to  wholly
owned  subsidiaries  of the  Company), pledge  or  otherwise encumber  shares of
capital stock of the Company  or any of its  subsidiaries or mortgage or  pledge
any  of its assets or create any Lien thereupon; (v) enter into, adopt, amend or
terminate any bonus, compensation,  severance, termination, or employee  benefit
arrangement  not required by  any such plan or  arrangement; (vi) acquire, sell,
lease, license, encumber, transfer or dispose  of any assets of the Company  and
its  subsidiaries; (vii)  change any of  the accounting  principles or practices
used by it,  except as may  be required as  a result of  a change in  law or  in
generally  accepted  accounting  principles;  (viii)  acquire  any  corporation,
partnership or other  business organization or  division thereof, authorize  any
new  capital expenditure not reflected in the Company's capital budget or settle
any litigation for amounts in excess  of $500,000 individually or $1,000,000  in
the  aggregate; (ix) make any tax election  or settle or compromise any material
tax liability;  (x)  pay,  discharge  or  satisfy  any  claims,  liabilities  or
obligations  outside the ordinary course or  not in accordance with their terms,
except where such  action would not  result in a  material adverse effect;  (xi)
enter   into  any  agreement  providing  for  the  acceleration  of  payment  or
performance or other  consequence as  a result  of a  change in  control of  the
Company;  (xii)  enter  into  any agreement  providing  for  any  license, sale,
assignment or otherwise transfer any patent rights or grant any covenant not  to
sue with respect to any of its patent rights or take such action with respect to
the  Company's Intellectual Property that would  have a material adverse effect;
or (xiii)  take  or agree  to  take  any action  which  would make  any  of  the
representations  or warranties of the Company  contained in the Merger Agreement
untrue or incorrect or would  result in any of the  conditions to the Offer  not
being satisfied.
 
    Notwithstanding  the above, the Company may adopt a shareholder rights plan,
issue rights  thereunder and  issue  securities upon  exercise of  such  rights;
provided,  however, that such rights plan exempts  the Offer and the Merger from
the events which trigger the exercise of such rights.
 
    ACCESS TO INFORMATION.  The Company will give Parent and Purchaser and their
representatives reasonable  access  to  all necessary  information.  Parent  and
Purchaser  agree to  be bound by  the Confidentiality Agreement  dated March 13,
1996 (described below).
 
    REASONABLE BEST EFFORTS.  Each of  the parties will use its reasonable  best
efforts to take all actions and do all things reasonably necessary to consummate
and make effective the transactions contemplated by the Merger Agreement.
 
    PUBLIC  ANNOUNCEMENTS.   Parent  and  Purchaser, on  the  one hand,  and the
Company, on the  other hand,  will consult with  each other  before issuing  any
press  release or  otherwise making  any public  statements with  respect to the
transactions contemplated by the Merger Agreement.
 
                                       17
<PAGE>
    INDEMNIFICATION.    The  surviving  corporation  will  keep  in  effect  the
provisions  in  its  Articles  of  Organization  and  By-Laws  with  respect  to
exculpation  of director and officer liability  and indemnification set forth in
the Restated Articles of  Organization and Amended and  Restated By-Laws of  the
Company  on the date of the Merger Agreement. From and after the Effective Time,
Parent will guarantee and cause the surviving corporation to perform all of  its
obligations  under  the Restated  Articles of  Organization  and By-Laws  of the
Company with respect to indemnification.
 
    Parent will  cause the  surviving  corporation to  use its  reasonable  best
efforts  to  maintain in  effect  for five  years  from the  Effective  Time, if
available, the  coverage  provided  by  the  current  directors'  and  officers'
liability  insurance policies maintained by the  Company with respect to matters
occurring prior to  the Effective  Time; provided, however,  that the  surviving
corporation  will not be required to incur  any annual premium in excess of 200%
of the  last annual  aggregate premium  paid prior  to the  date of  the  Merger
Agreement  for all current directors' and officers' liability insurance policies
maintained by the Company.
 
    NOTIFICATION OF CERTAIN  MATTERS.  The  Company will give  prompt notice  to
Parent  or Purchaser,  and Parent  or Purchaser will  give prompt  notice to the
Company, as the  case may be,  of (i)  the occurrence or  non-occurrence of  any
event which would be likely to cause any representation or warranty contained in
this  Agreement to be untrue or inaccurate  and (ii) any failure of the Company,
Parent or Purchaser, as the case may be, to comply with or satisfy any covenant,
condition or agreement under the Merger Agreement.
 
    TERMINATION OF STOCK  PLANS.  Prior  to the consummation  of the Offer,  the
Company's  Board of Directors  (or, if appropriate,  any committee thereof) will
adopt resolutions or take other actions necessary to ensure that, following  the
Effective Time, no participant in any stock, stock option, stock appreciation or
other  benefit plan of the  Company or any of its  subsidiaries or any holder of
any option will have any  right thereunder to acquire  any capital stock of  the
surviving corporation or any subsidiary thereof.
 
    NO  SOLICITATION.  The Merger Agreement  requires the Company immediately to
cease any  existing discussions  or  negotiations with  any third  parties  with
respect  to any inquiry, proposal or offer for a merger, consolidation, business
combination, sale  of  substantial  assets,  sale of  shares  of  capital  stock
(including,   without  limitation,  by  way  of   a  tender  offer)  or  similar
transactions involving the Company or  any of its subsidiaries (an  "Acquisition
Proposal").  The Company shall not, directly or indirectly, through any officer,
director, employee,  representative or  agent or  any of  its subsidiaries,  (i)
solicit,  initiate, continue or encourage an Acquisition Proposal, (ii) solicit,
initiate, continue  or  engage in  negotiations  or discussions  concerning,  or
provide  any non-public information or data to any person or entity relating to,
any Acquisition Proposal, or (iii) agree to approve or recommend any Acquisition
Proposal; provided, that if the  Company's Board of Directors determines,  after
receiving advice of its independent counsel, that to do so would be required for
the  discharge of its fiduciary obligations, the Company may, after receiving an
executed confidentiality agreement (with terms no less favorable to the  Company
than those contained in the Confidentiality Agreement entered into with Parent),
furnish  nonpublic  information  or  data  to,  or  enter  into  discussions  or
negotiations with,  any person  in connection  with an  unsolicited  Acquisition
Proposal or recommend an unsolicited Acquisition Proposal to the stockholders of
the  Company. The Company  will advise Parent of  all such nonpublic information
delivered to such person,  and will notify Parent  immediately (and in no  event
later than 24 hours) after receipt by the Company of any Acquisition Proposal or
any  request  for  non-public  information  in  connection  with  an Acquisition
Proposal or for access to the properties, books or records of the Company by any
person or entity that informs the Company that it is considering making, or  has
made, an Acquisition Proposal.
 
CONDITIONS TO THE CONSUMMATION OF THE MERGER
 
    The  obligations  of  the Company,  Parent  and Purchaser  under  the Merger
Agreement are subject  to the  satisfaction or,  if appropriate,  waiver of  the
following conditions:
 
        (a)  PURCHASE OF SHARES. Purchaser  shall have purchased Shares pursuant
    to the Offer.
 
                                       18
<PAGE>
        (b) STOCKHOLDER APPROVAL. If required  by Massachusetts law, the  Merger
    Agreement   shall  have  been  adopted  by   the  affirmative  vote  of  the
    stockholders of  the  Company  by  the requisite  vote  in  accordance  with
    Massachusetts law.
 
        (c)  NO  PROHIBITION.  No  order,  decree  or  ruling  or  other  action
    restraining, enjoining or otherwise prohibiting the Merger, which shall have
    been issued or taken by any court or other governmental body.
 
        (d) HSR ACT.  Any waiting period  applicable to the  HSR Act shall  have
    terminated or expired.
 
TERMINATION
 
    The  Merger Agreement provides  that the Merger  Agreement may be terminated
and the Merger may be abandoned at any  time prior to the Effective Time (i)  by
mutual  written consent of Parent, Purchaser and  the Company; (ii) by Parent or
the Company to the extent that performance is prohibited, enjoined or  otherwise
materially  restrained by any final, non-appealable judgment; (iii) by Parent or
the Company  if Purchaser  has terminated  the  Offer or  failed to  accept  for
purchase  and  pay for  Shares pursuant  to the  Offer by  June 30,  1996 unless
Purchaser failed to accept for purchase and pay for Shares pursuant to the Offer
as the result of the receipt by the  Company of an Acquisition Proposal or as  a
result of a failure of the applicable waiting period under the HSR Act to expire
or  the failure to obtain any necessary governmental or regulatory approvals, in
which case, if Purchaser has  failed to accept for  purchase and pay for  Shares
pursuant  to the Offer by September 30, 1996, and the failure to purchase Shares
by that date did not result from the failure by the party seeking termination to
fulfill any obligation under the Merger Agreement; (iv) by either Parent or  the
Company  if, prior to  the purchase of  Shares pursuant to  the Offer, there has
been a  material breach  by the  other party  of any  representation,  warranty,
covenant or agreement that has not been cured within twenty business days notice
of  such breach; (v) by either Parent or  the Company not sooner than three days
after the Company's notice to Parent of the Company's receipt of an  Acquisition
Proposal  determined  by  the Board  of  Directors  of the  Company  to  be more
favorable  to  the  Company  and  to  its  stockholders  than  the  transactions
contemplated  by the Merger Agreement  or (vi) by Parent  if the Company's Board
withdraws or modifies in a manner adverse to Parent or Purchaser its approval of
the Offer, the  Merger Agreement,  or the Merger  or its  recommendation to  the
Company's stockholders.
 
    If  the Merger Agreement is terminated pursuant to clause (v) or (vi) above,
the Company will pay Parent a non-refundable fee of $17,500,000.
 
SURVIVAL OF REPRESENTATIONS AND WARRANTIES
 
    The representations and warranties in the Merger Agreement shall not survive
beyond the  Effective Time,  except that  the covenants  and agreements  in  the
Merger Agreement shall survive in accordance with their respective terms.
 
AMENDMENT; EXTENSION; WAIVER
 
    Subject  to approval  by the  Board of the  Company in  the manner described
above under "Board Representation," the Merger  Agreement may be amended by  the
Company,  Parent and  Purchaser in  a writing  signed on  behalf of  each of the
parties; however,  after approval  of  the Merger  by  the stockholders  of  the
Company  (if required by  applicable law), no amendment  may decrease the Merger
Consideration  or  change   the  form  thereof   which  adversely  affects   the
stockholders without approval of such stockholders.
 
    Subject  to approval  by the  Board of the  Company in  the manner described
above under "Board Representation," at any time prior to the Effective Time, the
Company, on the one hand,  and Parent and Purchaser, on  the other hand, may  in
writing  (i) extend the  time for the  performance of any  of the obligations or
other  acts  of   the  other  party,   (ii)  waive  any   inaccuracies  in   the
representations  and warranties of the other  party or (iii) waive compliance by
the other party with any of the agreements or conditions contained in the Merger
Agreement.
 
                                       19
<PAGE>
EXPENSES
 
    Subject to the payment of  a fee by the Company  to Purchaser if the  Merger
Agreement  is terminated under certain circumstances,  each party shall bear its
own expenses  and  costs  in  connection  with  the  Merger  Agreement  and  the
transactions contemplated thereby.
 
GOVERNING LAW
 
    The  Merger Agreement shall be governed  by and construed in accordance with
the laws of the Commonwealth of Massachusetts.
 
    CONFIDENTIALITY AGREEMENT
 
    The following summary of the  Confidentiality Agreement does not purport  to
be  complete and is qualified in its  entirety by reference to the complete text
of the Confidentiality Agreement, which is  filed as an exhibit to the  Schedule
14D-1 and incorporated herein by reference.
 
    On  March 13, 1996, the Company  and Parent entered into the Confidentiality
Agreement providing for  the non-disclosure  of confidential  information to  be
provided   by  the  Company  to  Parent  and  by  Parent  to  the  Company.  The
Confidentiality Agreement provided that for a period of 16 days from the date of
the  Confidentiality  Agreement,  the  Company  would  not  initiate,   solicit,
encourage  or engage  in any  discussions with  a party  other than  Parent with
respect to any merger, consolidation or other business combination  transaction,
any sale, lease, exchange, transfer or other disposition of all or substantially
all  of the assets of  the Company, any tender offer  or exchange offer for more
than 20% of  the outstanding  shares of  any class  of the  Company's equity  or
voting  securities or any solicitation of  proxies with respect to the Company's
equity or voting securities in the election of directors or in a vote on any  of
the foregoing transactions (a "Specified Transaction").
 
    The  Confidentiality Agreement also provides that,  for a period of one year
from the  date  of the  Confidentiality  Agreement, without  the  prior  written
consent  of the Company, Parent will not (i) acquire, offer to acquire, or agree
to acquire any  voting securities or  any material assets  of the Company,  (ii)
solicit any proxies to vote any voting securities of the Company, (iii) make any
public  announcement or  submit any  proposal for  any extraordinary transaction
involving the Company, (iv) form, join or participate in any "group" as  defined
in  Section 13(d)(3) of the Exchange Act in connection with any of the foregoing
or (v) request the Company to amend or waive any of the foregoing provisions  in
a  manner  that would  be required  to be  disclosed publicly.  The restrictions
discussed in the previous  sentence will not  be binding upon  Parent if, on  or
after  the date  of the  Confidentiality Agreement, (a)  any person  or group of
persons (other than certain institutional investors not having any intention  to
change or influence control of the Company) acquires beneficial ownership of any
equity  or voting security of  the Company representing 15%  or more of the then
total outstanding shares of any such class of the Company's securities, (b)  the
Company  issues or commits to issue any  voting securities (other than shares of
Common Stock  or securities  convertible or  exchangeable for  shares of  Common
Stock), or (c) it is publicly announced or disclosed that any person or group of
persons  other than Parent,  the Company or any  of their respective affiliates,
proposes to effect or has effected a Specified Transaction.
 
11.  SOURCE AND AMOUNT OF FUNDS
    The total amount of funds required by Purchaser and Parent to consummate the
Offer and the Merger  and to pay  related fees and expenses  is estimated to  be
approximately  $885,000,000. Purchaser will obtain all funds required by it from
Parent. Parent will cause the required  funds to be made available to  Purchaser
and  Parent  expects to  obtain  all required  funds  from unsecured  short term
borrowings at market  interest rates. Such  borrowings may be  repaid by  Parent
from  time to time, in whole or in part, from internally generated funds or from
the proceeds of other borrowings.
 
12.  CERTAIN EFFECTS OF THE OFFER
    Following the  consummation of  the Offer,  Purchaser will  own at  least  a
majority  of  the  outstanding  Shares  of the  Company.  As  a  result  of such
ownership, Purchaser will be in a position to control the outcome of any  matter
voted  upon  at any  annual or  special meeting  of the  Company's stockholders,
including the  election of  directors and  the approval  of the  Merger and  the
adoption  of the Merger Agreement. If at least 90% of the outstanding Shares are
purchased by Purchaser in the Offer, the Board
 
                                       20
<PAGE>
of Directors of Purchaser will have the ability to approve the Merger and  adopt
the  Merger Agreement  without any action  by the remaining  stockholders of the
Company. If at least 90% of the Shares are purchased by Purchaser in the  Offer,
Purchaser  intends  so to  approve  the Merger  and  adopt the  Merger Agreement
without any action by the remaining stockholders of the Company.
 
    Parent and Purchaser have agreed to vote all Shares held by them in favor of
the Merger Agreement and the transactions contemplated thereby. Approval of  the
Merger  requires the affirmative  vote of a majority  of the outstanding Shares.
Accordingly, if the  Offer is consummated,  the approval of  the Merger and  the
adoption of the Merger Agreement by the Company's stockholders will be assured.
 
    In  the  Merger, each  remaining Share  (other than  Shares held  by Parent,
Purchaser or the Company or by any holders of Shares who properly exercise their
appraisal rights) will  be cancelled  and converted  into the  right to  receive
$45.00  per Share in  cash. Following the  Merger, the Company  will be a wholly
owned subsidiary of Purchaser.
 
    Promptly upon the purchase by Purchaser of Shares pursuant to the Offer  and
from  time to time thereafter, Purchaser will  be entitled to designate a number
of directors on the Company's Board of Directors equal to the product of (i) the
total number  of  directors  on  the  Company's  Board  of  Directors  and  (ii)
Purchaser's  percentage ownership of the outstanding  Shares of the Company. The
Company will either  increase the size  of the Company's  Board of Directors  or
secure   the  resignation  of  the  necessary  number  of  directors  to  enable
Purchaser's designees to  be elected to  the Company's Board  of Directors,  and
will cause such designees to be elected to the Company's Board of Directors.
 
    Following   the  election  or  appointment  of  Purchaser's  designees,  any
amendment of the Merger  Agreement or the Restated  Articles of Organization  or
By-laws  of the Company, any termination of the Merger Agreement by the Company,
and any extension by the Company of  the time for performance of obligations  or
the  waiver of any rights under the Merger  Agreement will require the vote of a
majority of  directors of  the  Company who  are  not Purchaser's  designees  or
employees of the Company.
 
    The  Shares are currently "margin securities", as such term is defined under
the rules of the Board of Governors of the Federal Reserve System (the  "Federal
Reserve  Board"), which has the effect,  among other things, of allowing brokers
to extend credit on the collateral of such securities. Following the Offer it is
possible that  the Shares  might no  longer constitute  "margin securities"  for
purposes  of the margin regulations of the Federal Reserve Board, in which event
such Shares could no longer be used as collateral for loans made by brokers.
 
13.  CERTAIN CONDITIONS OF THE OFFER
 
    Notwithstanding  any  other  provision  of  the  Offer,  the  obligation  of
Purchaser  to accept for payment or pay  for any Shares tendered pursuant to the
Offer shall  be  subject to  (the  following being  referred  to as  the  "Offer
Conditions")  (i) the Minimum  Condition, (ii) the  expiration or termination of
any applicable  waiting  period under  the  HSR  Act, (iii)  the  expiration  or
termination  of any  applicable waiting  period requirements  under any  laws or
regulations relating to the regulation  of monopolies or competition in  Germany
and (iv) to the satisfaction or waiver of the following conditions:
 
        (a)  NO PROHIBITION. There shall not  have been any action or proceeding
    brought by any  governmental authority  before any  court, or  any order  or
    preliminary  or  permanent injunction  entered in  any action  or proceeding
    before any court or governmental, administrative or regulatory authority  or
    any  statute,  rule, regulation,  legislation,  judgment or  order, enacted,
    entered, enforced, promulgated, amended, issued or deemed applicable to  the
    Offer or the Merger by any court, governmental, administrative or regulatory
    authority  which could have  the effect of: (i)  making illegal or otherwise
    restraining or prohibiting or imposing material penalties in connection with
    the making of  the Offer,  the acceptance for  payment of,  payment for,  or
    ownership  of,  some  or all  of  the  Shares by  Parent  or  Purchaser, the
    consummation of  the Offer  or the  Merger; (ii)  prohibiting or  materially
    limiting  the direct or indirect ownership or operation by the Company or by
    Parent of all  or any  material portion  of the  business or  assets of  the
    Company  and its  subsidiaries, taken  as a  whole, or  compelling Parent to
    dispose of or hold separate all or  any material portion of the business  or
    assets
 
                                       21
<PAGE>
    of  the Company and its  subsidiaries, taken as a whole,  as a result of the
    transactions  contemplated  by  the  Merger  Agreement;  (iii)  imposing  or
    confirming  material  limitations  on  the  ability  of  Parent  effectively
    directly or indirectly  to acquire  or hold or  to exercise  full rights  of
    ownership  of Shares, including,  without limitation, the  right to vote any
    Shares on all matters properly presented to the stockholders of the Company,
    including, without  limitation,  the adoption  and  approval of  the  Merger
    Agreement and the Merger or the right to vote any shares of capital stock of
    any  subsidiary of the  Company; or (iv) requiring  divestiture by Parent or
    Purchaser, directly or indirectly, of any Shares.
 
        (b) OUTSIDE  EVENTS.  There shall  not  have occurred  (i)  any  general
    suspension  of trading  in, or limitation  on prices for,  securities on any
    securities exchange or in the  over-the-counter market in the United  States
    (other  than a shortening  of trading hours or  any coordinated trading halt
    triggered solely as a result of a specified increase or decrease in a market
    index), (ii) the declaration  of a banking moratorium  or any suspension  of
    payments in respect of banks in the United States (whether or not mandatory)
    or  (iii) any  limitation (whether  or not  mandatory) by  any United States
    governmental authority or  agency on  the extension  of credit  by banks  or
    other financial institutions.
 
        (c)  PERFORMANCE.  The  Company  shall have  performed  in  all material
    respects its covenants and agreements under the Merger Agreement.
 
        (d)  REPRESENTATIONS  AND  WARRANTIES  TRUE.  The  representations   and
    warranties  of the Company set  forth in the Merger  Agreement shall be true
    and correct as of the Effective Time except where failure to be so true  and
    correct would not have a material adverse effect on the Company.
 
        (e)  NO TERMINATION. The Merger Agreement shall not have been terminated
    in accordance with its terms.
 
    Purchaser shall not be required to accept for payment or pay for any  Shares
tendered  pursuant to the Offer if any of the above conditions occurs, which, in
the reasonable judgment  of Purchaser in  any such case,  and regardless of  the
circumstances (including any action or omission by Purchaser) giving rise to any
such  condition makes it inadvisable to proceed with such acceptance for payment
or payments for Shares.
 
    The foregoing conditions are  for the sole benefit  of Purchaser and may  be
asserted  by Purchaser regardless  of the circumstances giving  rise to any such
condition or may be waived by Purchaser in whole or in part at any time or  from
time  to time in  its sole discretion. The  failure by Purchaser  at any time to
exercise any of the foregoing  rights shall not be deemed  a waiver of any  such
right,  the  waiver  of any  such  right  with respect  to  particular  facts or
circumstances shall not be deemed  a waiver with respect  to any other facts  or
circumstances,  and each such right shall be deemed an ongoing right that may be
asserted at any time or from time to time.
 
14.  DIVIDENDS AND DISTRIBUTIONS
 
    If the Company should (a) split,  combine or otherwise change the Shares  or
its  capitalization, (b) acquire currently outstanding Shares or otherwise cause
a reduction in the number of outstanding Shares or (c) issue or sell  additional
Shares,  shares of any other class of  capital stock, other voting securities or
any securities convertible into, or rights, warrants or options, conditional  or
otherwise,  to acquire, any of the foregoing,  then subject to the provisions of
Section 1 above, Purchaser, in its sole discretion, may make such adjustments as
it deems appropriate in the Offer Price and other terms of the Offer, including,
without limitation, the number or type of securities offered to be purchased.
 
    If the Company should declare or pay any cash dividend on the Shares or make
other distributions  on the  Shares or  issue with  respect to  the Shares,  any
additional  shares, shares  of any  other class  of capital  stock, other voting
securities or any securities convertible  into, or rights, warrants or  options,
conditional  or  otherwise,  to  acquire,  any  of  the  foregoing,  payable  or
distributable to stockholders of record on a  date prior to the transfer of  the
Shares purchased pursuant to the Offer to Purchaser or its nominee or transferee
on  the Company's  stock transfer  records, then,  subject to  the provisions of
Section 1 above, (a) the Offer Price  may, in the sole discretion of  Purchaser,
be reduced by the amount of
 
                                       22
<PAGE>
any  such  cash dividend  or cash  distribution and  (b) the  whole of  any such
noncash dividend,  distribution or  issuance  to be  received by  the  tendering
stockholders will (i) be received and held by the tendering stockholders for the
account  of  Purchaser  and  will  be  required  to  be  promptly  remitted  and
transferred by each tendering stockholder to  the Depositary for the account  of
Purchaser,  accompanied by appropriate documentation of transfer, or (ii) at the
direction of Purchaser, be exercised for the benefit of Purchaser, in which case
the proceeds of such  exercise will promptly be  remitted to Purchaser.  Pending
such remittance and subject to applicable law, Purchaser will be entitled to all
rights  and  privileges as  owner of  any  such noncash  dividend, distribution,
issuance or proceeds and may withhold the entire Offer Price or deduct from  the
Offer  Price the amount or value thereof, as determined by Purchaser in its sole
discretion.
 
15.  CERTAIN LEGAL MATTERS; REGULATORY APPROVALS
 
    GENERAL
 
    Except as  described  below, Purchaser  is  not aware  of  any  governmental
license  or regulatory permit that appears to be material to the business of the
Company and its subsidiaries, taken as a whole, that might be adversely affected
by Purchaser's acquisition of the Company's Shares as contemplated herein or  of
any  approval or other action by  any governmental, administrative or regulatory
authority or  agency,  domestic or  foreign,  that  would be  required  for  the
acquisition  or ownership of Shares by  Purchaser as contemplated herein. Should
any such approval or  other action be required,  Purchaser and Parent  currently
contemplate  that  such  approval or  other  action  will be  sought.  Except as
otherwise expressly described in this  Section 15, Purchaser does not  presently
intend  to delay the  acceptance for payment  of or payment  for Shares tendered
pursuant to  the Offer  pending the  outcome of  any such  matter. Purchaser  is
unable  to predict  whether it may  determine that  it is required  to delay the
acceptance for payment of or payment  for Shares tendered pursuant to the  Offer
pending  the outcome of any such matter. There can be no assurance that any such
approval or other  action, if  needed, would be  obtained or  would be  obtained
without  substantial conditions or that the  failure to obtain any such approval
or other  action might  not  result in  consequences  adverse to  the  Company's
business  or that certain parts  of the Company's business  might not have to be
disposed of, any of which could cause Purchaser to decline to accept for payment
or pay for any Shares tendered. See  Section 13 above for certain conditions  to
the Offer.
 
    ANTITRUST.
 
    Under the HSR Act and the rules that have been promulgated thereunder by the
Federal  Trade Commission (the "FTC"),  certain acquisition transactions may not
be consummated unless certain  information has been  furnished to the  Antitrust
Division of the Department of Justice (the "Antitrust Division") and the FTC and
certain  waiting period requirements have been satisfied. The purchase of Shares
of  the  Company  by  Purchaser  pursuant  to  the  Offer  is  subject  to  such
requirements.
 
    Under the provisions of the HSR Act applicable to the Offer, the purchase of
Shares  under  the  Offer  may  be consummated  following  the  expiration  of a
15-calendar-day waiting period following the filing by Parent of a  Notification
and  Report Form with respect to the Offer, unless Parent receives a request for
additional information or  documentary material from  the Antitrust Division  or
the  FTC or unless  early termination of  the waiting period  is granted. Parent
expects that such filing will be made on or about Friday, April 5, 1996 and such
waiting period will expire at 11:59 p.m.  on or about Saturday, April 20,  1996.
If, within their initial 15-day waiting period, either the Antitrust Division or
the  FTC  requests additional  information or  documentary material  from Parent
concerning the Offer, the  waiting period will be  extended and would expire  at
11:59  p.m., New  York City time,  on the tenth  calendar day after  the date of
substantial compliance by Parent  with such request. Only  one extension of  the
waiting period pursuant to a request for additional information is authorized by
the HSR Act. Thereafter, such waiting period may be extended only by court order
or  with  the consent  of  Parent. In  practice,  complying with  a  request for
additional information or documentary material can take a significant amount  of
time.  In  addition, if  the Antitrust  Division or  the FTC  raises substantive
issues in connection with a proposed
 
                                       23
<PAGE>
transaction, the parties  frequently engage  in negotiations  with the  relevant
governmental agency concerning possible means of addressing those issues and may
agree to delay consummation of the transaction while such negotiations continue.
 
    A request is being made pursuant to the HSR Act for early termination of the
waiting period applicable to the Offer. There can be no assurance, however, that
the  15 calendar day HSR Act waiting  period will be terminated early. Shares of
the Company will not be accepted for  payment or paid for pursuant to the  Offer
until  the expiration  or earlier termination  of the  applicable waiting period
under the HSR Act. See Section 13. Any extension of the waiting period will  not
give rise to any withdrawal rights not otherwise provided for by applicable law.
See  Section 4. If  Purchaser's acquisition of  Shares is delayed  pursuant to a
request by  the Antitrust  Division or  the FTC  for additional  information  or
documentary  material pursuant to the  HSR Act, the Offer  may, but need not, be
extended.
 
    The FTC and the Antitrust Division frequently scrutinize the legality  under
the  antitrust laws  of transactions  such as the  acquisition of  Shares of the
Company by  Purchaser  pursuant  to the  Offer.  At  any time  before  or  after
Purchaser's  purchase of Shares pursuant to the Offer, the Antitrust Division or
the FTC could take such action under the antitrust laws as it deems necessary or
desirable in the public  interest, including seeking to  enjoin the purchase  of
Shares  pursuant to the Offer  or the consummation of  the Merger or seeking the
divestiture of Shares acquired  by Purchaser or  the divestiture of  substantial
assets  of  Parent or  its  subsidiaries, or  the  Company or  its subsidiaries.
Private parties  may also  bring legal  action under  the antitrust  laws  under
certain  circumstances. Purchaser does not believe  that the consummation of the
Offer will result  in a  violation of  any applicable  antitrust laws.  However,
there  can be no  assurance that a  challenge to the  Offer on antitrust grounds
will not be made or, if such a challenge is made, of the result thereof.
 
    FOREIGN REGULATIONS.
 
    Under German laws and regulations  relating to the regulation of  monopolies
and  competition,  certain acquisition  transactions may  not be  consummated in
Germany unless  certain information  has been  furnished to  the German  Federal
Cartel  Office (the  "FCO") and  certain waiting  period requirements  have been
satisfied. The purchase of  Shares of the Company  by Purchaser pursuant to  the
Offer  and the consummation of  the Merger may be  subject to such requirements,
with regard to the German subsidiaries of the Company and Parent. Parent expects
to file such information  on or about  April 10, 1996;  and such waiting  period
will  expire on or about May 10, 1996 or  may be extended by the FCO for a total
of four  months  from  the  date  of  the  filing.  Parent  will  request  early
termination  of the waiting  period, although there  can be no  assurance of the
outcome of such request. Purchaser does not believe that the consummation of the
Offer will result in a violation of any applicable law or regulation in  Germany
relating  to the regulation of monopolies and competition. However, there can be
no assurance that a challenge to the Offer on such grounds will not be made, or,
if such a challenge is made, of the result thereof.
 
16.  FEES AND EXPENSES
 
    Goldman, Sachs & Co.  are acting as Dealer  Managers in connection with  the
Offer  and serving  as financial advisor  to Parent and  Purchaser in connection
with the proposed acquisition of the Company. In consideration of Goldman, Sachs
& Co. acting as the Dealer Managers in connection with the Offer and the Merger,
Parent has agreed to pay Goldman, Sachs & Co. as follows: if at least 50% of the
outstanding Shares of the Company, or at  least 50% of the assets (based on  the
book  value  thereof) of  the  Company are  acquired by  Parent  in one  or more
transactions, Goldman, Sachs & Co.  will be entitled to  receive a fee equal  to
0.55%  of the aggregate consideration, not to  exceed $5 million and if some but
less than 50% of  the Shares or  assets of the Company  are acquired by  Parent,
Goldman,  Sachs & Co. will be entitled to  a mutually acceptable fee of not less
than $3 million. In the event that the Merger Agreement is terminated,  Goldman,
Sachs  & Co. will be entitled to a transaction fee of 10% of any termination fee
payable to Parent  but such  transaction fee  is not  to exceed  $3 million.  In
addition, Parent and Purchaser have agreed to reimburse Goldman, Sachs & Co. for
all reasonable out-of-pocket expenses incurred, including reasonable fees of its
counsel, and to indemnify Goldman, Sachs & Co.
 
                                       24
<PAGE>
against certain liabilities and expenses in connection with the Offer, including
certain liabilities under the federal securities laws. Goldman, Sachs & Co. have
from  time to time, and continue  to, render various investment banking services
to Parent and its affiliates, for which they are paid customary fees.
 
    Purchaser has retained Georgeson  & Company Inc. to  act as the  Information
Agent,  and  The First  National Bank  of Boston  to act  as the  Depositary, in
connection with the Offer. The Information  Agent may contact holders of  Shares
by  mail, telephone,  telex, telegraph  and personal  interview and  may request
brokers, dealers and other nominee  stockholders to forward the Offer  materials
to  beneficial owners.  Each of  the Information  Agent and  the Depositary will
receive reasonable  and customary  compensation for  their respective  services,
will  be reimbursed  for certain reasonable  out-of-pocket expenses  and will be
indemnified against  certain liabilities  and expenses  in connection  with  the
Offer, including certain liabilities under the federal securities laws.
 
    Except as set forth above, Purchaser will not pay any fees or commissions to
any  broker or dealer or other person  for soliciting tenders of Shares pursuant
to the Offer. Brokers, dealers, commercial banks and trust companies will,  upon
request,  be reimbursed by Purchaser for customary mailing and handling expenses
incurred by them in forwarding the Offer materials to their customers.
 
17. MISCELLANEOUS
 
    The offer is being  made solely by  this Offer to  Purchase and the  related
Letter  of Transmittal and is being made to  all holders of Shares. The Offer is
not being made to, nor will tenders be accepted from or on behalf of, holders of
Shares of the Company residing  in any jurisdiction in  which the making of  the
Offer  or the acceptance thereof would not be in compliance with the securities,
blue sky or  other laws  of such jurisdiction.  However, Purchaser  may, in  its
discretion,  take such action as it may deem  necessary to make the Offer in any
jurisdiction and extend the Offer to holders of Shares in such jurisdiction.  In
any  jurisdiction where the securities, blue sky or other laws require the Offer
to be made by a licensed broker or  dealer, the Offer will be deemed to be  made
on  behalf of Purchaser by the Dealer Managers or one or more registered brokers
or dealers that are licensed under the laws of such jurisdiction.
 
    Parent and  Purchaser have  filed  with the  Commission the  Schedule  14D-1
pursuant  to Rule  14d-3 under  the Exchange  Act containing  certain additional
information with respect to the Offer. Such Schedule and any amendments thereto,
including exhibits,  may  be  examined  and copies  may  be  obtained  from  the
principal  office of the Commission  in the manner set  forth in Section 7 above
(except that  they  will  not  be  available at  the  regional  offices  of  the
Commission).
 
    NO  PERSON  HAS  BEEN  AUTHORIZED  TO  GIVE  ANY  INFORMATION  OR  MAKE  ANY
REPRESENTATION ON BEHALF OF PURCHASER OR  PARENT NOT CONTAINED IN THIS OFFER  TO
PURCHASE OR IN THE LETTER OF TRANSMITTAL AND, IF GIVEN OR MADE, SUCH INFORMATION
OR REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED.
 
                                          AAC ACQUISITION, INC.
 
April 4, 1996
 
                                       25
<PAGE>
                                                                      SCHEDULE I
 
            DIRECTORS AND EXECUTIVE OFFICERS OF PARENT AND PURCHASER
 
A.  DIRECTORS AND EXECUTIVE OFFICERS OF PARENT
 
    The  following table  sets forth the  name, present  principal occupation or
employment and material  occupation, positions,  offices or  employment for  the
past  five  years  of each  director  and  executive officer  of  Parent. Unless
otherwise indicated  below, the  address of  each director  and officer  is  100
Abbott  Park Road, Abbott Park, Illinois 60064 and each such person is a citizen
of the United States.
 
<TABLE>
<CAPTION>
                                                             PRESENT PRINCIPAL OCCUPATION
NAME AND                                                           OF EMPLOYMENT AND
BUSINESS ADDRESS                                             FIVE-YEAR EMPLOYMENT HISTORY
- ------------------------------------  ---------------------------------------------------------------------------
<S>                                   <C>
K. Frank Austen, M.D................  Dr. Austen has been a director since 1983. He is the Theodore B. Bayles
                                       Professor of Medicine on the faculty of Harvard Medical School. Dr. Austen
                                       also is a director of Humana Inc.
Duane L. Burnham....................  Mr. Burnham has served as a director of Parent since 1985, as Chairman of
                                       the Board of Parent since 1990 and as Chief Executive Officer of Parent
                                       since 1989. He also is a director of Sara Lee Corporation and Evanston
                                       Hospital Corporation.
H. Laurance Fuller..................  Mr. Fuller has been a director since 1988. He has served as Chairman and
                                       Chief Executive Officer of Amoco Corporation ("Amoco") since 1991. From
                                       1983 to 1995, Mr. Fuller was the President of Amoco. He also is a director
                                       of The Chase Manhattan Corporation and The Chase Manhattan Bank, N.A. and
                                       Motorola, Inc.
The Lord Hayhoe PC..................  Lord Hayhoe has been a director since 1989. Bernard Hayhoe is a British
                                       subject. Created a Life Peer in August 1992 and now a Member of the House
                                       of Lords, he was an elected Member of the U.K. House of Commons 1970-92.
                                       He was appointed a Privy Councillor in 1985. He served in the British
                                       Government as Minister of Health, Treasury Minister of State, Civil
                                       Service Minister, and Army Minister during the years 1979 to 1986. Lord
                                       Hayhoe is a Fellow of the Institution of Mechanical Engineers and an
                                       Honorary Fellow of Birkbeck College, London, and a director of the Portman
                                       Building Society. He became Chairman of the Guys and St. Thomas Hospital,
                                       London in April, 1993.
Thomas R. Hodgson...................  Mr. Hodgson has served as President and Chief Operating Officer of Parent
                                       since 1990. He joined Parent in 1972 and has held various operational
                                       positions with Parent.
Allen F. Jacobson...................  Mr. Jacobson has been a director since 1993. He served as Chairman of the
                                       Board and Chief Executive Officer of Minnesota Mining & Manufacturing from
                                       1986 until 1991. Mr. Jacobson also serves as a director of Sara Lee
                                       Corporation, Deluxe Corporation, Mobile Corporation, Northern States Power
                                       Company, Potlatch Corporation, Prudential Insurance Company, Silicon
                                       Graphics, Inc., US WEST, Inc. and Valmont Industries, Inc.
David A. Jones......................  Mr. Jones has been a director since 1982. He has been the Chairman and
                                       Chief Executive Officer of Humana Inc. since co-founding the company in
                                       1961.
</TABLE>
 
                                      I-1
<PAGE>
<TABLE>
<CAPTION>
                                                             PRESENT PRINCIPAL OCCUPATION
NAME AND                                                           OF EMPLOYMENT AND
BUSINESS ADDRESS                                             FIVE-YEAR EMPLOYMENT HISTORY
- ------------------------------------  ---------------------------------------------------------------------------
<S>                                   <C>
Boone Powell, Jr....................  Mr. Powell has been a director since 1985. He has served as President and
                                       Chief Executive Officer of Baylor University Medical Center since 1980.
                                       Mr. Powell is also President and Chief Executive Officer of Baylor Health
                                       Care System and a director of Comerica Bank-Texas, Physician Reliance
                                       Network and Cable Healthcare.
Addison Barry Rand..................  Mr. Rand has been a director since 1992. He has served as Executive Vice
                                       President of Xerox Corporation since 1992. From 1986 to 1992, he was
                                       President of Xerox Corporation's U.S. Marketing Group. Mr. Rand also
                                       serves as a director of Ameritech Corporation and Honeywell, Inc.
W. Ann Reynolds, Ph.D...............  Dr. Reynolds has been a director since 1980. She has served as Chancellor
                                       of The City University of New York since 1990. Dr. Reynolds also is a
                                       director of Humana, Inc., Maytag Corporation and Owens-Corning Fiberglas
                                       Corp.
William D. Smithburg................  Mr. Smithburg has been a director since 1982. He currently serves as
                                       Chairman, President and Chief Executive Officer of The Quaker Oats
                                       Company. Mr. Smithburg became President and Chief Executive Officer in
                                       1981, Chairman and Chief Executive Officer in 1983 and also served as
                                       President from November 1990 to January 1993 and from November 1995 to the
                                       present. He is also a director of Northern Trust Corporation, Corning
                                       Incorporated and Prime Capital Corp.
John R. Walter......................  Mr. Walter has been a director since 1990. He has served as Chairman and
                                       Chief Executive Officer of R.R. Donnelley & Sons Company since 1989. Mr.
                                       Walter also is a director of Dayton Hudson Corporation, Deere & Company,
                                       and Evanston Hospital.
William L. Weiss....................  Mr. Weiss has been a director since 1984. He became Chairman and Chief
                                       Executive Officer of Ameritech Corporation in 1983 and served in that
                                       capacity until January 1994 when he was named Chairman of the Board. Since
                                       May 1994 Mr. Weiss has been Chairman Emeritus of that Board. Mr. Weiss
                                       also is a director of The Quaker Oats Company, Merrill Lynch & Co., Inc.
                                       and Tenneco Corporation.
Joy A. Amundson.....................  Ms. Amundson has served as Senior Vice President, Chemical and Agricultural
                                       Products of Parent since 1995. From 1994 to 1995 she served as Vice
                                       President, HealthSystems. Prior to 1994 she served as Vice President,
                                       Corporate Hospital Marketing.
Catherine V. Babington..............  Ms. Babington has served as Vice President, Investor Relations and Public
                                       Affairs of Parent since 1995. Prior to 1995, she served as Director,
                                       Corporate Communications.
Gary R. Byers.......................  Mr. Byers has served as Vice President, Internal Audit of Parent since
                                       1993. Prior to 1993, he served as Divisional Vice President, Corporate
                                       Auditing.
Paul N. Clark.......................  Mr. Clark has served as Senior Vice President, Pharmaceutical Operations of
                                       Parent.
</TABLE>
 
                                      I-2
<PAGE>
<TABLE>
<CAPTION>
                                                             PRESENT PRINCIPAL OCCUPATION
NAME AND                                                           OF EMPLOYMENT AND
BUSINESS ADDRESS                                             FIVE-YEAR EMPLOYMENT HISTORY
- ------------------------------------  ---------------------------------------------------------------------------
<S>                                   <C>
Gary P. Coughlan....................  Mr. Coughlan has served as Senior Vice President, Finance and Chief
                                       Financial Officer of Parent.
Jose M. de Lasa.....................  Mr. de Lasa has served as Senior Vice President, Secretary and General
                                       Counsel of Parent since 1994. From 1991 to 1994, he served as Vice
                                       President and Associate General Counsel of Bristol-Myers Squibb Company.
                                       In 1994 he also became Secretary of such company.
Kenneth W. Farmer...................  Mr. Farmer has served as Vice President, Management Information Services
                                       and Administration of Parent.
Thomas C. Freyman...................  Mr. Freyman has served as Vice President and Treasurer of Parent since
                                       1991. Prior to that, in 1991 he served as Treasurer, Abbott International
                                       Ltd.
Richard A. Gonzalez.................  Mr. Gonzalez has served as Vice President, HealthSystems of Parent since
                                       1995. Prior to 1995 he served as Divisional Vice President and General
                                       Manager, U.S./Canada Diagnostics.
John G. Kringel.....................  Mr. Kringel has served as Senior Vice President, Hospital Products of
                                       Parent.
John F. Lussen......................  Mr. Lussen has served as Vice President, Taxes of Parent.
Thomas M. McNally...................  Mr. McNally has served as Senior Vice President, Ross Products of Parent
                                       since 1993. Prior to 1993, he served as Senior Vice President, Chemical
                                       and Agricultural Products.
David V. Milligan...................  Dr. Milligan has served as Senior Vice President, Chief Scientific Officer
                                       of Parent since 1994. From 1992 to 1994 he served as Vice President,
                                       Pharmaceutical Products Research and Development. Prior to 1992, he served
                                       as Vice President, Diagnostic Products Research and Development.
Richard H. Morehead.................  Mr. Morehead has served as Vice President, Corporate Planning and
                                       Development of Parent.
Theodore A. Olson...................  Mr. Olson has served as Vice President and Controller of Parent.
Robert L. Parkinson, Jr.............  Mr. Parkinson has served as Senior Vice President, International Operations
                                       of Parent since 1995. From 1993 to 1995 he served as Senior Vice
                                       President, Chemical and Agricultural Products. Prior to 1993, he served as
                                       Vice President, European Operations.
Ellen M. Walvoord...................  Ms. Walvoord has served as Senior Vice President, Human Resources of Parent
                                       since 1995. From 1991 to 1995 she served as Vice President, Investor
                                       Relations and Public Affairs. Prior to that in 1991, Ms. Walvoord served
                                       as Vice President, Investor Relations and served as Director, Corporate
                                       Communications.
Miles D. White......................  Mr. White has served as Senior Vice President, Diagnostic Operations of
                                       Parent since 1994. From 1993 to 1994 he served as Vice President,
                                       Diagnostic Systems and Operations, from 1992 to 1993 he served as
                                       Divisional Vice President and General Manager, Diagnostic Systems and
                                       Operations. Prior to 1992, he served as Divisional Vice President and
                                       General Manager, Hospital Laboratory Sector.
</TABLE>
 
                                      I-3
<PAGE>
<TABLE>
<CAPTION>
                                                             PRESENT PRINCIPAL OCCUPATION
NAME AND                                                           OF EMPLOYMENT AND
BUSINESS ADDRESS                                             FIVE-YEAR EMPLOYMENT HISTORY
- ------------------------------------  ---------------------------------------------------------------------------
<S>                                   <C>
Don G. Wright.......................  Mr. Wright has served as Vice President, Corporate Quality Assurance and
                                       Regulatory Affairs of Parent.
Lance B. Wyatt......................  Mr. Wyatt has served as Vice President, Corporate Engineering of Parent
                                       since 1995. Prior to 1995, he served as Divisional Vice President, Quality
                                       Assurance and Regulatory Affairs.
</TABLE>
 
B.  DIRECTORS AND EXECUTIVE OFFICERS OF PURCHASER
 
    The following table sets forth the name, business address, present principal
occupation  or  employment  and  material  occupations,  positions,  offices  or
employment  for the past  five years of  each director and  executive officer of
Purchaser. Unless otherwise indicated  below, the address  of each director  and
officer  is: 100  Abbott Park  Road, Abbott Park,  Illinois 60064  and each such
person is a citizen of the United States.
 
<TABLE>
<CAPTION>
                                                             PRESENT PRINCIPAL OCCUPATION
NAME AND                                                           OF EMPLOYMENT AND
BUSINESS ADDRESS                                             FIVE-YEAR EMPLOYMENT HISTORY
- ------------------------------------  ---------------------------------------------------------------------------
<S>                                   <C>
Gary P. Coughlan....................  Mr. Coughlan serves as sole director, Vice President and Treasurer of
                                       Purchaser. He also has served as Senior Vice President, Finance and Chief
                                       Financial Officer of Parent. He was elected as a corporate officer of
                                       Parent in 1990.
Miles D. White......................  Mr. White serves as President of Purchaser. He also has served as Senior
                                       Vice President, Diagnostic Operations of Parent since 1994. From 1993 to
                                       1994 he served as Vice President, Diagnostic Systems and Operations of
                                       Parent, from 1992 to 1993 he served as Divisional Vice President and
                                       General Manager, Diagnostic Systems and Operations of such company. Prior
                                       to 1992, he served as Divisional Vice President and General Manager,
                                       Hospital Laboratory Sector of such company.
John F. Lussen......................  Mr. Lussen serves as Vice President of Purchaser. He has served as Vice
                                       President, Taxes of Parent.
</TABLE>
 
                                      I-4
<PAGE>
    Facsimile copies of the Letter  of Transmittal, properly completed and  duly
signed, will be accepted. The Letter of Transmittal, certificates for Shares and
any  other required documents should be sent or delivered by each stockholder of
the Company or such stockholder's broker, dealer, commercial bank, trust company
or other nominee to the Depositary, at one of the addresses set forth below:
 
<TABLE>
<S>                          <C>                          <C>
                            DEPOSITARY FOR THE OFFER IS:
                          THE FIRST NATIONAL BANK OF BOSTON
         BY MAIL:            BY FACSIMILE TRANSMISSION:            BY HAND:
   Shareholder Services            (617) 575-2232          BancBoston Trust Company
         Division                  (617) 575-2233                 of New York
       P.O. Box 1889         (For Eligible Institutions    55 Broadway, Third Floor
    Mail Stop 45-02-53                  Only)                 New York, New York
Boston, Massachusetts 02105     CONFIRM BY TELEPHONE:
      (800) 730-4001               (800) 730-4001            BY OVERNIGHT COURIER:
                                                            The First National Bank
                                                                   of Boston
                                                             Shareholder Services
                                                                   Division
                                                               150 Royall Street
                                                              Mail Stop: 45-02-53
                                                          Canton, Massachusetts 02021
</TABLE>
 
    Questions and requests  for assistance  may be directed  to the  Information
Agent or the Dealer Managers at their respective addresses and telephone numbers
listed  below.  Additional  copies of  this  Offer  to Purchase,  the  Letter of
Transmittal  and  other  tender  offer  materials  may  be  obtained  from   the
Information  Agent  as  set  forth  below  and  will  be  furnished  promptly at
Purchaser's expense. You may  also contact the Dealer  Managers or your  broker,
dealer,   commercial  bank,  trust  company  or  other  nominee  for  assistance
concerning the Offer.
 
                    THE INFORMATION AGENT FOR THE OFFER IS:
 
                                     [LOGO]
 
                               Wall Street Plaza
                            New York, New York 10005
                                 (800) 223-2065
 
                     THE DEALER MANAGERS FOR THE OFFER ARE:
                              GOLDMAN, SACHS & CO.
 
                                85 Broad Street
                            New York, New York 10004
                  In New York State: (212) 902-1000 (collect)
                    Other Areas: (800) 323-5678 (toll free)
 
                                      I-5
<PAGE>
                                 [Letter Head]
 
                                                                        ANNEX II
 
                                 March 29, 1996
 
Board of Directors
MediSense, Inc.
266 Second Avenue
Waltham, MA 02154
Dear Sirs:
 
    MediSense,   Inc.  ("MediSense"  or   the  "Company"),  Abbott  Laboratories
("Abbott" or the "Buyer") and AAC Acquisition, Inc., a Massachusetts corporation
and a wholly owned subsidiary of Buyer (the "Merger Sub"), have entered into  an
Agreement and Plan of Merger dated March 29, 1996 (the "Agreement"). Pursuant to
the  Agreement, the Merger Sub will commence a tender offer (the "Tender Offer")
to purchase all the outstanding common stock, $.01 par value per share, and  all
the  outstanding class  B common stock,  $.01 par value,  (together, the "Common
Stock"), of MediSense at a price of $45.00 per share, net to the seller in cash.
The Agreement also provides that following such tender offer, Merger Sub will be
merged with and into MediSense (the  "Merger"), and that each outstanding  share
of  Common Stock, other than  the shares held by Abbott  or the Company, will be
converted into  the right  to receive  $45.00 in  cash. You  have requested  our
opinion  as to whether  the consideration to  be received by  the holders of the
Common Stock pursuant to the Agreement is fair from a financial point of view to
such stockholders.
 
    Alex. Brown & Sons Incorporated ("Alex. Brown"), as a customary part of  its
investment banking business, is engaged in the valuation of businesses and their
securities   in   connection   with   mergers   and   acquisitions,   negotiated
underwritings, secondary  distributions of  securities, private  placements  and
valuations for corporate and other purposes. We have served as financial advisor
to  the Company  in connection with  the Merger and  will receive a  fee for our
services, a substantial portion of which is contingent upon the consummation  of
the Merger. Alex. Brown served as underwriter to MediSense in its initial public
offering of Common Stock in June 1994 and its follow-on offering of Common Stock
in  February 1995.  Alex. Brown  maintains a  market in  MediSense and regularly
publishes research reports regarding the healthcare industry and the  businesses
and securities of publicly owned companies in that industry, including MediSense
and Abbott.
 
    In  connection with this opinion, we have reviewed the Agreement and certain
publicly  available  financial  information  concerning  MediSense  and  certain
internal  financial  analyses  and  other information  furnished  to  us  by the
Company. We  have also  held  discussions with  senior management  of  MediSense
regarding  the business and prospects of the  Company.  In addition, we have (i)
reviewed the reported  price and  trading activity for  MediSense Common  Stock,
(ii)  compared certain financial and stock market information for MediSense with
similar information for  certain publicly traded  companies, (iii) reviewed  the
financial  terms of certain recent business combinations and (iv) performed such
other studies  and analyses  and taken  into account  such other  matters as  we
deemed necessary.
 
    We  have  assumed and  relied  upon, without  independent  verification, the
accuracy and completeness of the information reviewed by us for purposes of this
opinion. With respect to financial  projections and information relating to  the
prospects  of  the  Company, we  have  assumed  that such  information  has been
reasonably prepared  and reflects  the best  currently available  estimates  and
judgments  of  management  of the  Company  as  to the  likely  future financial
prospects of the Company. In addition, we have not made an independent valuation
or appraisal of the assets of the  Company (nor have we been furnished with  any
such  valuation or appraisal), nor  have we made any  physical inspection of the
properties or assets of the Company.  Our opinion is based on market,  economic,
financial and other conditions as they exist and can be evaluated as of the date
of this letter.
 
    It  is understood that  this letter is  for the information  of the Board of
Directors of the Company and may not  be used for any other purpose without  our
prior written consent, except that this opinion
<PAGE>
Board of Directors
MediSense, Inc.
March 29, 1996
may  be included  in its  entirety in any  filing made  by the  Company with the
Securities and Exchange  Commission with  respect to  the Tender  Offer and  the
Merger. In addition, we express no opinion as to whether the stockholders of the
Company should tender their shares of Common Stock in the Tender Offer.
 
    Based  upon and subject to the foregoing, it  is our opinion that, as of the
date of this letter, the cash consideration to be received by the holders of the
Common Stock pursuant to the Agreement is fair from a financial point of view to
such stockholders.
 
                                          Very truly yours,
 
                                          ALEX. BROWN & SONS INCORPORATED
 
                                          --------------------------------------

<PAGE>
                             LETTER OF TRANSMITTAL
                                TO TENDER SHARES
                                       OF
                     COMMON STOCK AND CLASS B COMMON STOCK
                                       OF
                                MEDISENSE, INC.
             PURSUANT TO THE OFFER TO PURCHASE DATED APRIL 4, 1996
                                       OF
                             AAC ACQUISITION, INC.
                          A WHOLLY OWNED SUBSIDIARY OF
                              ABBOTT LABORATORIES
 
           THE OFFER AND WITHDRAWAL RIGHTS EXPIRE AT 12:00 MIDNIGHT,
  NEW YORK CITY TIME, ON WEDNESDAY, MAY 1, 1996, UNLESS THE OFFER IS EXTENDED.
 
To: THE FIRST NATIONAL BANK OF BOSTON, DEPOSITARY
 
<TABLE>
<S>                                     <C>                                     <C>
               BY MAIL:                       BY FACSIMILE TRANSMISSION:                       BY HAND:
    Shareholder Services Division                   (617) 575-2232                     BancBoston Trust Company
            P.O. Box 1889                           (617) 575-2233                           of New York
          Mail Stop 45-02-53               (For Eligible Institutions Only)            55 Broadway, Third Floor
     Boston, Massachusetts 02105                                                          New York, New York
            (800) 730-4001
</TABLE>
 
<TABLE>
<S>                                     <C>                                     <C>
                                           CONFIRM FACSIMILE BY TELEPHONE:              BY OVERNIGHT COURIER:
                                                    (800)730-4001                 The First National Bank of Boston
                                               (For Confirmation Only)              Shareholder Services Division
                                                                                          150 Royall Street
                                                                                         Mail Stop: 45-02-53
                                                                                     Canton, Massachusetts 02021
</TABLE>
 
    DELIVERY OF THIS LETTER OF TRANSMITTAL TO AN ADDRESS OTHER THAN AS SET FORTH
ABOVE  OR TRANSMISSION OF INSTRUCTIONS VIA  A FACSIMILE TRANSMISSION TO A NUMBER
OTHER THAN AS SET FORTH ABOVE WILL NOT CONSTITUTE A VALID DELIVERY.
 
    THE INSTRUCTIONS  ACCOMPANYING THIS  LETTER OF  TRANSMITTAL SHOULD  BE  READ
CAREFULLY BEFORE THIS LETTER OF TRANSMITTAL IS COMPLETED.
 
    This Letter of Transmittal is to be used by stockholders if certificates for
Shares  (as defined below)  are to be  forwarded herewith or,  unless an Agent's
Message (as defined in the Offer to Purchase) is utilized, if delivery of Shares
is to  be  made  by book-entry  transfer  to  the Depositary's  account  at  The
Depository  Trust Company or Philadelphia  Depository Trust Company (hereinafter
collectively referred to  as the "Book-Entry  Transfer Facilities") pursuant  to
the  procedures set forth under "The Tender  Offer -- 3. Procedure for Tendering
Shares" in the Offer  to Purchase dated April  4, 1996. Stockholders who  tender
Shares   by  book-entry   transfer  are   referred  to   herein  as  "Book-Entry
Stockholders."
 
    Stockholders who  cannot  deliver  their  Shares  and  all  other  documents
required hereby to the Depositary on or prior to the Expiration Date (as defined
in  the Offer to Purchase) or who  cannot complete the procedures for book-entry
transfer on a timely
<PAGE>
basis, must tender their  Shares pursuant to  the guaranteed delivery  procedure
set  forth under "The Tender Offer --  3. Procedure for Tendering Shares" in the
Offer to  Purchase. See  Instruction 2.  Delivery  of documents  to one  of  the
Book-Entry Transfer Facilities does not constitute delivery to the Depositary.
<TABLE>
<S>                                                     <C>                     <C>                     <C>
                                        DESCRIPTION OF SHARES TENDERED -- COMMON STOCK
 
<CAPTION>
   NAME(S) AND ADDRESS(ES) OF REGISTERED HOLDER(S)
    (Please fill in, if blank, exactly as name(s)                                  SHARES TENDERED
           appear(s) on Share Certificates                              (ATTACH ADDITIONAL LIST IF NECESSARY)
<S>                                                     <C>                     <C>                     <C>
<CAPTION>
                                                                                     TOTAL NUMBER
                                                                                      OF SHARES
                                                             CERTIFICATE            REPRESENTED BY            NUMBER OF
                                                              NUMBER(S)*           CERTIFICATE(S)*        SHARES TENDERED**
<S>                                                     <C>                     <C>                     <C>
                                                             TOTAL SHARES
  *Need not be completed by stockholders tendering by book-entry transfer.
 **Unless otherwise indicated, it will be assumed that all Shares represented by any certificates delivered to the Depositary
   are being tendered. See Instruction 4.
</TABLE>
<TABLE>
<S>                                                     <C>                     <C>                     <C>
                                    DESCRIPTION OF SHARES TENDERED -- CLASS B COMMON STOCK
 
<CAPTION>
   NAME(S) AND ADDRESS(ES) OF REGISTERED HOLDER(S)
    (Please fill in, if blank, exactly as name(s)                                  SHARES TENDERED
           appear(s) on Share Certificates                              (ATTACH ADDITIONAL LIST IF NECESSARY)
<S>                                                     <C>                     <C>                     <C>
<CAPTION>
                                                                                     TOTAL NUMBER
                                                                                      OF SHARES
                                                             CERTIFICATE            REPRESENTED BY            NUMBER OF
                                                              NUMBER(S)*           CERTIFICATE(S)*        SHARES TENDERED**
<S>                                                     <C>                     <C>                     <C>
                                                             TOTAL SHARES
  *Need not be completed by stockholders tendering by book-entry transfer.
 **Unless otherwise indicated, it will be assumed that all Shares represented by any certificates delivered to the Depositary
   are being tendered. See Instruction 4.
</TABLE>
 
                                  INSTRUCTIONS
             FORMING PART OF THE TERMS AND CONDITIONS OF THE OFFER
 
     1.    GUARANTEE OF  SIGNATURES.   Except as  otherwise provided  below, all
signatures on  this Letter  of Transmittal  must be  guaranteed by  a  financial
institution  (including most banks, savings  and loan associations and brokerage
houses) which  is a  participant  in the  Securities Transfer  Agents  Medallion
Program,  the New York  Stock Exchange Medallion Signature  Program or the Stock
Exchange Medallion  Program  (an  "Eligible Institution").  Signatures  on  this
Letter  of Transmittal need not be guaranteed  (a) if this Letter of Transmittal
is signed by the registered holder(s) of the Shares (which term, for purposes of
this document, shall include any participant  in one of the Book-Entry  Transfer
Facilities  whose name appears  on a security  position listing as  the owner of
Shares) tendered herewith and such holder(s) have not completed the  instruction
entitled  "Special Delivery  Instruments" or  "Special Payment  Instructions" on
this Letter of Transmittal or (b) if such Shares are tendered for the account of
an Eligible Institution. See Instruction 5.
 
     2.   DELIVERY  OF  LETTER  OF  TRANSMITTAL AND  SHARES.    This  Letter  of
Transmittal  is to be used if certificates are to be forwarded herewith pursuant
to the procedures set forth in "The  Tender Offer -- 3. Procedure for  Tendering
Shares"  of the  Offer to  Purchase. Certificates  for all  physically delivered
Shares, or a confirmation of a book-entry transfer into the Depositary's account
at  one  of  the  Book-Entry   Transfer  Facilities  of  all  Shares   delivered
electronically,  as well  as a  properly completed  and duly  executed Letter of
Transmittal (or facsimile thereof) (or, in the case of a book-entry delivery, an
Agent's Message) and any other documents required by this Letter of Transmittal,
must be received  by the Depositary  at one of  its addresses set  forth on  the
front  page of this  Letter of Transmittal by  the Expiration Date. Stockholders
who cannot  deliver  their  Shares  and all  other  required  documents  to  the
Depositary  by  the Expiration  Date must  tender their  Shares pursuant  to the
guaranteed delivery procedure set forth in "The Tender Offer -- 3. Procedure for
Tendering Shares" of the Offer to Purchase. Pursuant to such procedure: (a) such
tender must  be made  by or  through  an Eligible  Institution, (b)  a  properly
completed  and duly executed Notice of  Guaranteed Delivery substantially in the
form provided  by  the Purchaser  must  be received  by  the Depositary  by  the
Expiration Date and (c) the certificates for all physically delivered Shares, or
a  confirmation of a book-entry transfer into the Depositary's account at one of
the Book-Entry Transfer  Facilities of all  Shares delivered electronically,  as
well  as  a  properly completed  and  duly  executed Letter  of  Transmittal (or
facsimile thereof)  (or,  in the  case  of  a book-entry  delivery,  an  Agent's
Message) and any other documents required by this Letter of Transmittal, must be
received  by the Depositary  within five Nasdaq Stock  Market trading days after
the date of execution of such Notice of Guaranteed Delivery, all as provided  in
"The Tender Offer -- 3. Procedure for Tendering Shares." If Shares are forwarded
separately to the Depositary, each must be accompanied by a duly executed Letter
of Transmittal (or facsimile thereof).
 
    The  method of  delivering Shares, the  Letter of Transmittal  and all other
required documents including delivery through Book-Entry Transfer Facilities, is
at the option and sole risk of  the tendering stockholder and the delivery  will
be  deemed made only when actually received by the Depositary. If delivery is by
mail, registered  mail  with  return  receipt  requested,  properly  issued,  is
recommended.  In all cases,  sufficient time should be  allowed to ensure timely
delivery.
 
    No alternative,  conditional  or contingent  tenders  will be  accepted.  By
executing  this  Letter of  Transmittal  (or facsimile  thereof),  the tendering
stockholder waives any right to receive any notice of the acceptance for payment
of the Shares.
 
     3.  INADEQUATE  SPACE.   If the space  provided herein  is inadequate,  the
certificate  numbers and/or the number of Shares  should be listed on a separate
schedule attached hereto and separately signed on each page thereof in the  same
manner as this Letter of Transmittal is signed.
<PAGE>
     4.    PARTIAL  TENDERS  (NOT  APPLICABLE  TO  STOCKHOLDERS  WHO  TENDER  BY
BOOK-ENTRY TRANSFER).    If  fewer  than  all  the  Shares  represented  by  any
certificate  delivered to the Depositary are to  be tendered, fill in the number
of Shares  which are  to  be tendered  in the  box  entitled "Number  of  Shares
Tendered."  In such  case, a  new certificate  for the  remainder of  the Shares
represented by the old  certificate will be sent  to the person(s) signing  this
Letter  of Transmittal, unless otherwise provided in the appropriate box on this
Letter of Transmittal, as  promptly as practicable  following the expiration  or
termination  of the Offer.  All Shares represented  by certificates delivered to
the Depositary will be deemed to have been tendered unless otherwise indicated.
 
     5.  SIGNATURES ON LETTER OF TRANSMITTAL; STOCK POWERS AND ENDORSEMENTS.  If
this Letter of Transmittal is signed  by the registered holder(s) of the  Shares
tendered hereby, the signature(s) must correspond with the name(s) as written on
the  face  of the  certificates without  alteration,  enlargement or  any change
whatsoever.
 
    If any of  the Shares  tendered hereby  are held of  record by  two or  more
persons, all such persons must sign this Letter of Transmittal.
 
    If  any of the Shares  tendered hereby are registered  in different names on
different certificates, it  will be necessary  to complete, sign  and submit  as
many  separate Letters  of Transmittal as  there are  different registrations of
certificates.
 
    If this Letter of Transmittal is  signed by the registered holder(s) of  the
Shares tendered hereby, no endorsements of certificates or separate stock powers
are  required unless payment of the purchase price  is to be made, or Shares not
tendered or not purchased are  to be returned, in the  name of any person  other
than  the registered  holder(s). Signatures  on any  such certificates  or stock
powers must be guaranteed by an Eligible Institution.
 
    If this  Letter  of  Transmittal  is  signed by  a  person  other  than  the
registered  holder(s)  of  the  Shares  tendered  hereby,  certificates  must be
endorsed or  accompanied by  appropriate stock  powers, in  either case,  signed
exactly as the name(s) of the registered holder(s) appear(s) on the certificates
for  such Shares. Signatures(s) on any such certificates or stock powers must be
guaranteed by an Eligible Institution.
 
    If this Letter of Transmittal or any certificate or stock power is signed by
a trustee,  executor, administrator,  guardian, attorney-in-fact,  officer of  a
corporation  or other person  acting in a  fiduciary or representative capacity,
such person should so indicate when signing, and proper evidence satisfactory to
the Purchaser of the authority of such person so to act must be submitted.
 
     6.  STOCK TRANSFER TAXES.  The Purchaser will pay any stock transfer  taxes
with respect to the sale and transfer of any Shares to its or its order pursuant
to  the Offer. If, however, payment  of the purchase price is  to be made to, or
Shares not tendered  or not purchased  are to be  returned in the  name of,  any
person  other than the registered holder(s), or if a transfer tax is imposed for
any reason other than the sale or  transfer of Shares to the Purchaser  pursuant
to  the Offer, then the  amount of any stock  transfer taxes (whether imposed on
the registered holder(s), such other person or otherwise) will be deducted  from
the purchase price unless satisfactory evidence of the payment of such taxes, or
exemption therefrom, is submitted herewith.
 
    EXCEPT  AS PROVIDED  IN THIS  INSTRUCTION 6,  IT WILL  NOT BE  NECESSARY FOR
TRANSFER TAX STAMPS TO BE AFFIXED TO  THE CERTIFICATES LISTED IN THIS LETTER  OF
TRANSMITTAL.
 
     7.    SPECIAL PAYMENT  AND DELIVERY  INSTRUCTIONS.   If  the check  for the
purchase price  of any  Shares purchased  is to  be issued,  or any  Shares  not
tendered or not purchased are to be returned, in the name of a person other than
the  person(s)  signing  this Letter  of  Transmittal  or if  the  check  or any
certificates for  Shares not  tendered or  not  purchased are  to be  mailed  to
someone  other than the person(s)  signing this Letter of  Transmittal or to the
person(s) signing this Letter of Transmittal at an address other than that shown
above, the appropriate boxes on this Letter of Transmittal should be  completed.
Stockholders tendering Shares by book-entry transfer may request that Shares not
purchased  be  credited  to  such  account at  any  of  the  Book-Entry Transfer
Facilities  as   such  stockholder   may   designate  under   "Special   Payment
Instructions."  If no such instructions are given, any such Shares not purchased
will be returned by crediting the account at the Book-Entry Transfer  Facilities
designated above.
 
     8.  SUBSTITUTE FORM W-9.  Under the federal income tax laws, the Depositary
will  be required to backup  withhold 31% of the amount  of any payments made to
certain stockholders  pursuant to  the  Offer. In  order  to avoid  such  backup
withholding,  each tendering stockholder, and,  if applicable, each other payee,
must provide the Depositary with such stockholder's or payee's correct  taxpayer
identification  number and certify that such stockholder or payee is not subject
to such  backup withholding  by completing  the Substitute  Form W-9  set  forth
above.  In general,  if a  stockholder or payee  is an  individual, the taxpayer
identification number is the Social Security  number of such individual. If  the
Depositary  is not provided with the correct taxpayer identification number, the
stockholder or payee may  be subject to  a $50 penalty  imposed by the  Internal
Revenue  Service  ("IRS").  Certain  stockholders  or  payees  (including, among
others, all corporations  and certain  foreign individuals) are  not subject  to
these  backup withholding  and reporting requirements.  In order  to satisfy the
Depositary that  a foreign  individual qualifies  as an  exempt recipient,  such
stockholder or payee must submit a statement, signed under penalties of perjury,
attesting  to that individual's  exempt status. Such  statements can be obtained
from the Depositary. For further  information concerning backup withholding  and
instructions  for completing the Substitute Form  W-9 (including how to obtain a
taxpayer identification number if you  do not have one  and how to complete  the
Substitute  Form W-9  if Shares  are held  in more  than one  name), consult the
enclosed GUIDELINES  FOR  CERTIFICATION  OF TAXPAYER  IDENTIFICATION  NUMBER  ON
SUBSTITUTE FORM W-9.
 
    Failure  to  complete the  Substitute Form  W-9 will  not, by  itself, cause
Shares to  be deemed  invalidly  tendered, but  may  require the  Depositary  to
withhold  31% of the amount  of any payments made  pursuant to the Offer. Backup
withholding is not an additional federal income tax. Rather, the federal  income
tax  liability of a person subject to  backup withholding will be reduced by the
amount of tax  withheld. If withholding  results in an  overpayment of taxes,  a
refund  may be obtained  provided that the required  information is furnished to
the IRS.
 
    NOTE: FAILURE TO COMPLETE AND RETURN  THE SUBSTITUTE FORM W-9 MAY RESULT  IN
BACKUP  WITHHOLDING OF 31%  OF ANY PAYMENTS  MADE TO YOU  PURSUANT TO THE OFFER.
PLEASE  REVIEW   THE  ENCLOSED   GUIDELINES   FOR  CERTIFICATION   OF   TAXPAYER
IDENTIFICATION NUMBER ON SUBSTITUTE FORM W-9 FOR ADDITIONAL DETAILS.
 
     9.   REQUESTS FOR ASSISTANCE OR ADDITIONAL COPIES.  Requests for assistance
or additional copies of the Offer to Purchase and this Letter of Transmittal may
be obtained from the  Information Agent or Dealer  Managers at their  respective
addresses or telephone numbers set forth below.
 
    10.    LOST,  DESTROYED  OR  STOLEN  CERTIFICATES.    If  any certificate(s)
representing Shares has been lost,  destroyed or stolen, the stockholder  should
promptly  notify the Depositary.  Instructions will then be  given to what steps
must be taken to obtain a replacement certificate(s). The Letter of  Transmittal
and  related documents  cannot be processed  until the  procedures for replacing
such missing certificate(s) have been followed.
<PAGE>
                    NOTE: SIGNATURES MUST BE PROVIDED BELOW
                PLEASE READ ACCOMPANYING INSTRUCTIONS CAREFULLY
 
<TABLE>
<S>        <C>
/ /        CHECK HERE IF TENDERED SHARES ARE BEING DELIVERED BY BOOK-ENTRY TRANSFER TO THE DEPOSITARY'S ACCOUNT AT ONE OF
           THE BOOK-ENTRY TRANSFER FACILITIES AND COMPLETE THE FOLLOWING:
           Name of Tendering Institution
           Account No.  at
           / / The Depository Trust Company
           / / Philadelphia Depository Trust Company
           Transaction Code No.
/ /        CHECK HERE IF TENDERED SHARES ARE BEING DELIVERED PURSUANT TO A NOTICE OF GUARANTEED DELIVERY PREVIOUSLY  SENT
           TO THE DEPOSITARY AND COMPLETE THE FOLLOWING:
           Name(s) of Registered Stockholder(s)
           Window Ticket Number (if any)
           Date of Execution of Notice of Guaranteed Delivery
           Name of Institution which Guaranteed Delivery
           If delivery is by book entry transfer:
           Name of Tendering Institution
           / / DTC / / PHILADEP (check one) Account No.
           Transaction Code No.
</TABLE>
 
<PAGE>
Ladies and Gentlemen:
 
    The  undersigned hereby  tenders to  AAC Acquisition,  Inc., a Massachusetts
corporation ("Purchaser") and  wholly owned subsidiary  of Abbott  Laboratories,
the  above-described shares  of Common  Stock, par  value $.01  per share and/or
shares of Class  B Common  Stock, par value  $.01 per  share (collectively,  the
"Shares")  of  MediSense,  Inc., a  Massachusetts  corporation  (the "Company"),
pursuant to the Purchaser's offer to purchase all of the outstanding Shares at a
price of $45.00 per Share, net to the seller in cash, without interest  thereon,
upon  the terms and subject to the conditions set forth in the Offer to Purchase
dated April 4, 1996, receipt of which is hereby acknowledged, and in this Letter
of Transmittal (which together constitute the "Offer").
 
    Subject to,  and  effective  upon,  acceptance for  payment  of  the  Shares
tendered  herewith in accordance with the terms  of the Offer, including, if the
Offer is extended or amended, the terms and conditions of any such extension  or
amendment,  the undersigned hereby  sells, assigns and transfers  to or upon the
order of the Purchaser all  right, title and interest in  and to all the  Shares
that  are  being  tendered hereby  or  orders  the registration  of  such Shares
delivered by  book-entry  transfer  (and  any and  all  other  Shares  or  other
securities  issued or issuable in respect thereof  on or after April 4, 1996 and
any  or   all  dividends   thereon  or   distributions  with   respect   thereto
(collectively, "Distributions") and irrevocably appoints the Depositary the true
and  lawful agent and  attorney-in-fact of the undersigned  with respect to such
Shares (and all Distributions), with full  power of substitution (such power  of
attorney  being deemed to be an irrevocable  power coupled with an interest), to
(a) deliver  certificates  for  such  Shares  (and  all  such  other  shares  or
securities), or transfer ownership of such Shares (and all Distributions) on the
account books maintained by any of the Book-Entry Transfer Facilities, together,
in  any such case, with all accompanying evidences of transfer and authenticity,
to or upon the  order of the  Purchaser upon receipt by  the Depositary, as  the
undersigned's  agent, of  the purchase price,  (b) present such  Shares (and all
Distributions) for transfer  on the  books of the  Company and  (c) receive  all
benefits  and  otherwise exercise  all rights  of  beneficial ownership  of such
Shares (and all Distributions), all in accordance with the terms of the Offer.
 
    The undersigned hereby irrevocably appoints Miles D. White, Gary P. Coughlan
and Jose M. de Lasa and each  of them, the attorneys-in-fact and proxies of  the
undersigned,  each with full  power of substitution, to  exercise all voting and
other rights of the undersigned in such  manner as each such attorney and  proxy
or  his substitute shall in his sole discretion deem proper, with respect to all
of the  Shares tendered  hereby which  have  been accepted  for payment  by  the
Purchaser  prior to  the time  of any  vote or  other action  at any  meeting of
stockholders of the  Company (whether annual  or special and  whether or not  an
adjourned  meeting), by written consent or otherwise. This power of attorney and
proxy is  coupled  with  an  interest  and is  irrevocable  and  is  granted  in
consideration  of, and  is effective  upon, the  acceptance for  payment of such
Shares by  the  Purchaser  in accordance  with  the  terms of  the  Offer.  Such
acceptance for payment shall revoke, without any further action, any other power
of attorney or proxy granted by the undersigned at any time with respect to such
Shares,  and no subsequent power of attorney or proxies will be given or will be
executed by the undersigned (and if given or executed, will not be deemed to  be
effective). The undersigned understands that the Purchaser reserves the right to
require  that,  in  order  for  such  Shares  to  be  deemed  validly  tendered,
immediately upon  the Purchaser's  acceptance for  payment of  such Shares,  the
Purchaser is able to exercise full voting rights with respect to such Shares and
other securities, including voting at any meeting of stockholders.
 
    The undersigned hereby represents and warrants that the undersigned has full
power  and authority  to tender,  sell, assign and  transfer the  Shares and all
Distributions tendered hereby and that when the same are accepted for payment by
the Purchaser,  the  Purchaser  will  acquire  good  and  marketable  title  and
unencumbered  ownership  thereto, free  and  clear of  all  liens, restrictions,
charges, security interests,  and encumbrances  and not subject  to any  adverse
claims.  The undersigned will, upon request,  execute and deliver any additional
documents deemed by the Depositary or the Purchaser to be necessary or desirable
to  complete  the  sale,  assignment  and   transfer  of  the  Shares  and   all
Distributions  tendered hereby. In addition, the undersigned will promptly remit
and transfer to  the Depositary for  the account  of the Purchaser  any and  all
Distributions   in  respect  of  the  Shares  tendered  hereby,  accompanied  by
appropriate  documentation  of   transfer  and,  pending   such  remittance   or
appropriate assurance thereof, the Purchaser shall be entitled to all rights and
privileges  as  owner of  any such  Distributions, and  may withhold  the entire
purchase price or deduct from the purchase price of Shares tendered hereby,  the
amount or value thereof, as determined by the Purchaser in its sole discretion.
 
    All  authority herein conferred or agreed  to be conferred shall survive the
death or incapacity of  the undersigned, and any  obligation of the  undersigned
hereunder  shall be binding upon the heirs, personal representatives, successors
and assigns of the undersigned.  Except as stated in  the Offer, this tender  is
irrevocable.
 
    The  undersigned understands that  tenders of Shares pursuant  to any one of
the procedures described under "The Tender  Offer -- 3. Procedure for  Tendering
Shares"  in the Offer to Purchase and in the instructions hereto will constitute
a binding agreement between the undersigned and the Purchaser upon the terms and
subject to the conditions of the Offer.
 
    The undersigned recognizes  that, under certain  circumstances set forth  in
the Offer to Purchase, the Purchaser may terminate or amend the Offer or may not
be required to accept for payment any of the Shares tendered herewith.
 
    Unless  otherwise  indicated  under "Special  Payment  Instructions," please
issue the check for the purchase price and/or return any Shares not tendered  or
accepted  for  payment  in the  name(s)  of the  undersigned.  Similarly, unless
otherwise indicated under "Special Delivery Instructions," please mail the check
for the purchase  price and/or  return any  Share certificates  not tendered  or
accepted  for  payment  (and  accompanying  documents,  as  appropriate)  to the
undersigned at the address  shown below the  undersigned's signature(s). In  the
event   that  both   "Special  Payment   Instructions"  and   "Special  Delivery
Instructions" are  completed, please  issue  the check  for the  purchase  price
and/or return any Shares not tendered or accepted for payment in the name(s) of,
and  deliver said check and/or return certificates  to, the person or persons so
indicated. Stockholders tendering Shares by book-entry transfer may request that
any Shares  not accepted  for  payment be  returned  by crediting  such  account
maintained  at  such  Book-Entry  Transfer  Facility  as  such  stockholder  may
designate by making an appropriate  entry under "Special Payment  Instructions."
The  undersigned recognizes that the Purchaser has no obligation pursuant to the
"Special Payment  Instructions" to  transfer any  Shares from  the name  of  the
registered  holder thereof if the  Purchaser does not accept  for payment any of
such Shares.
<PAGE>
 
<TABLE>
<S>                                             <C>
         SPECIAL PAYMENT INSTRUCTIONS                   SPECIAL DELIVERY INSTRUCTIONS
       (SEE INSTRUCTIONS 1, 5, 6 AND 7)                (SEE INSTRUCTIONS 1, 5, 6 AND 7)
 
   To be completed ONLY if the check for the      To be completed ONLY if the check for the
 purchase price of Shares purchased or stock     purchase price of Shares purchased or stock
 certificates for Shares not tendered or not     certificates for Shares not tendered or not
  purchased are to be issued in the name of      purchased are to be mailed to someone other
     someone other than the undersigned.        than the undersigned or to the undersigned at
     Issue check and/or certificates to:          an address other than that shown below the
                     Name                                undersigned's signature(s).
                  (PLEASE PRINT)                      Mail check and/or certificates to:
                   Address                                           Name
- ----------------------------------------------                  (PLEASE PRINT)
                  (ZIP CODE)                                       Address
- ----------------------------------------------  ----------------------------------------------
    (TAXPAYER IDENTIFICATION NO. OR SOCIAL                        (ZIP CODE)
                SECURITY NO.)
        (COMPLETE SUBSTITUTE FORM W-9)
</TABLE>
 
                                   SIGN HERE
                  (PLEASE COMPLETE SUBSTITUTE FORM W-9 BELOW)
X
                            SIGNATURE(S) OF OWNER(S)
 
Dated , 1996
 
Name(s)
                                     (PLEASE PRINT)
 
- ------------------------------------------------------------------------
 
Capacity (full title)
 
Address
 
- ----------------------------------------------------------------
                               (INCLUDE ZIP CODE)
 
Area Code and Telephone No.
 
Tax Identification or Social Security No.
                   (COMPLETE SUBSTITUTE W-9 ON REVERSE SIDE)
 
  (Must be signed by registered holder(s) exactly as name(s) appear(s) on  stock
certificate(s)  or on a security position  listing or by person(s) authorized to
become registered holder(s) by certificates and documents transmitted  herewith.
If  signature is by  a trustee, executor,  administrator, guardian, attorney-in-
fact, officer  of  a  corporation or  other  person  acting in  a  fiduciary  or
representative capacity, please set forth full title and see Instruction 5.)
 
                           GUARANTEE OF SIGNATURE(S)
                           (SEE INSTRUCTIONS 1 AND 5)
 
Name of Firm
 
Authorized Signature
 
Name
 
Address
 
Area Code and Telephone Number
 
Dated , 1996
 
<PAGE>
                 TO BE COMPLETED BY ALL TENDERING STOCKHOLDERS
                              (SEE INSTRUCTION 8)
 
<TABLE>
<S>                                  <C>                                      <C>
                             PAYER'S NAME: [ ------------------------------------------]
 SUBSTITUTE                          PART I--PLEASE PROVIDE YOUR TIN IN THE
 FORM W-9                            BOX AT THE RIGHT AND CERTIFY BY SIGNING           Social security number
 DEPARTMENT OF THE TREASURY          AND DATING BELOW.                                           or
 INTERNAL REVENUE SERVICE
 PAYER'S REQUEST FOR                                                               Employer identification number
 TAXPAYER IDENTIFICATION
 NUMBER (TIN)
 Certification. -- Under penalties of perjury, I certify that:
 (1)  The number shown on this form is  my correct taxpayer identification number (or I  am waiting for a number to be
     issued to me);
 (2) I am not subject to backup  withholding because (a) I am exempt from  backup withholding, or (b) I have not  been
     notified by the Internal Revenue Service ("IRS") that I am subject to backup withholding as a result of a failure
     to  report all  interest or dividends,  or (c)  the IRS has  notified me  that I am  no longer  subject to backup
     withholding.
 CERTIFICATION INSTRUCTIONS -- You must  cross out item (2) above  if you have been notified  by the IRS that you  are
 currently  subject to backup withholding because of underreporting or dividends on your tax return. However, if after
 being notified by the IRS that you were subject to backup withholding you received another notification from the  IRS
 that you are no longer subject to backup withholding, do not cross out such item (2).
SIGNATURE DATE , 1996
</TABLE>
 
NOTE: FAILURE  TO COMPLETE AND RETURN THIS FORM MAY RESULT IN BACKUP WITHHOLDING
      OF 31% OF ANY PAYMENTS  MADE TO YOU PURSUANT  TO THE OFFER. PLEASE  REVIEW
      THE  ENCLOSED  GUIDELINES  FOR  CERTIFICATION  OF  TAXPAYER IDENTIFICATION
      NUMBER ON SUBSTITUTE FORM W-9 FOR ADDITIONAL DETAILS.
 
      YOU MUST COMPLETE  THE FOLLOWING  CERTIFICATE IF  YOU ARE  AWAITING A  TAX
      IDENTIFICATION NUMBER.
             CERTIFICATE OF AWAITING TAXPAYER IDENTIFICATION NUMBER
 
    I  certify under penalties of perjury  that a taxpayer identification number
has not  been issued  to  me, and  either  (1) I  have  mailed or  delivered  an
application  to  receive a  taxpayer  identification number  to  the appropriate
Internal Revenue Service Center or Social Security Administration Office or  (2)
I intend to mail or deliver an application in the near future. I understand that
if I do not provide a taxpayer identification number by the time of payment, 31%
of  all reportable payments made  to me will be  withheld, but that such amounts
will be refunded to me if I then provide a Taxpayer Identification Number within
sixty (60) days.
 
Signature ______________________________________ Date __________________________
<PAGE>
    Facsimile copies of the Letter  of Transmittal, properly completed and  duly
executed,  will be accepted.  The Letter of  Transmittal, certificates of Shares
and any other required documents should be sent or delivered by each stockholder
of the Company or  his broker, dealer, commercial  bank, trust company or  other
nominee to the Depositary at one of its addresses set forth below:
 
<TABLE>
<S>                                     <C>                                     <C>
                                             DEPOSITARY FOR THE OFFER IS:
                                          THE FIRST NATIONAL BANK OF BOSTON
               BY MAIL:                       BY FACSIMILE TRANSMISSION:            BY HAND OR OVERNIGHT COURIER:
    Shareholder Services Division                   (617) 575-2232                    Banc Boston Trust Company
            P.O. Box 1889                           (617) 575-2233                           of New York
          Mail Stop 45-02-53               (For Eligible Institutions Only)            55 Broadway, Third Floor
     Boston, Massachusetts 02105                                                          New York, New York
            (800) 730-4001
</TABLE>
 
<TABLE>
<S>                                     <C>                                     <C>
                                           CONFIRM FACSIMILE BY TELEPHONE:              BY OVERNIGHT COURIER:
                                                    (800)730-4001                 The First National Bank of Boston
                                               (For Confirmation Only)              Shareholder Services Division
                                                                                          150 Royall Street
                                                                                         Mail Stop: 45-02-53
                                                                                     Canton, Massachusetts 02021
</TABLE>
 
    Questions  and requests  for assistance may  be directed  to the Information
Agent or the Dealer Managers at their respective addresses and telephone numbers
listed below.  Additional  copies of  this  Offer  to Purchase,  the  Letter  of
Transmittal   and  other  tender  offer  materials  may  be  obtained  from  the
Information Agent  as  set  forth  below, and  will  be  furnished  promptly  at
Purchaser's  expense. You may  also contact the Dealer  Managers or your broker,
dealer,  commercial  bank,  trust  company  or  other  nominee  for   assistance
concerning this Offer.
 
                           THE INFORMATION AGENT IS:
 
                                     [LOGO]
 
                               Wall Street Plaza
                            New York, New York 10005
                                 1-800-223-2064
 
                     THE DEALER MANAGERS FOR THE OFFER ARE:
 
                              GOLDMAN, SACHS & CO.
                                85 Broad Street
                            New York, New York 10004
                  In New York State: (212) 902-1000 (collect)
                    Other Areas: (800) 323-5678 (toll free)

<PAGE>
                           OFFER TO PURCHASE FOR CASH
                     ALL OUTSTANDING SHARES OF COMMON STOCK
                            AND CLASS B COMMON STOCK
                                       OF
                                MEDISENSE, INC.
                                       AT
                              $45.00 NET PER SHARE
                                       BY
                             AAC ACQUISITION, INC.
                          A WHOLLY OWNED SUBSIDIARY OF
                              ABBOTT LABORATORIES
 
 THE  OFFER AND WITHDRAWAL RIGHTS EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY TIME,
 ON WEDNESDAY, MAY 1, 1996, UNLESS THE OFFER IS EXTENDED.
 
                                                                   April 4, 1996
 
To Our Clients:
 
    Enclosed for your  consideration are the  Offer to Purchase  dated April  4,
1996  (the "Offer  to Purchase") and  the related Letter  of Transmittal (which,
together with any amendments or supplements thereto, constitute the "Offer")  in
connection  with the offer by AAC Acquisition, Inc., a Massachusetts corporation
(the "Purchaser") and wholly owned subsidiary of Abbott Laboratories to purchase
all of the outstanding shares of MediSense, Inc.'s Common Stock, $.01 par  value
per  share, and Class  B Common Stock,  $.01 par value  per share (together, the
"Shares"), at a price of  $45.00 per Share, net to  the seller in cash,  without
interest  thereon, upon the terms and conditions  set forth in the Offer. We are
(or our nominee is) the holder of record of the Shares held for your account.  A
tender  of  such Shares  can be  made only  by us  as the  holder of  record and
pursuant to your instructions. THE LETTER OF TRANSMITTAL IS FURNISHED TO YOU FOR
YOUR INFORMATION ONLY AND CANNOT BE USED BY YOU TO TENDER SHARES HELD BY US  FOR
YOUR ACCOUNT.
 
    THE BOARD OF DIRECTORS OF MEDISENSE, INC. HAS UNANIMOUSLY APPROVED THE OFFER
AND  THE MERGER  AND RECOMMENDS  THAT STOCKHOLDERS  ACCEPT THE  OFFER AND TENDER
THEIR SHARES.
 
    We request instructions as to  whether you wish us to  tender any or all  of
the  Shares held  by us  for your  account, upon  the terms  and subject  to the
conditions set forth in the Offer.
 
    Please note carefully the following:
 
    1.  The tender price is $45.00 per Share, net to the seller in cash, without
       interest thereon, upon the terms and subject to the conditions set  forth
       in the Offer.
 
    2.    The Offer,  proration  period and  withdrawal  rights expire  at 12:00
       Midnight, New York City time, on Wednesday, May 1, 1996, unless the Offer
       is extended.
 
    3.  The Offer is being made for all of the Shares of Common Stock and  Class
       B Common Stock.
 
    4.   THE  OFFER IS  CONDITIONED UPON,  AMONG OTHER  THINGS, (1)  THERE BEING
       VALIDLY TENDERED AND NOT  PROPERLY WITHDRAWN PRIOR  TO THE EXPIRATION  OF
       THE OFFER A NUMBER OF SHARES WHICH CONSTITUTES AT LEAST A MAJORITY OF THE
       OUTSTANDING  SHARES OF MEDISENSE, INC. ON  A FULLY DILUTED BASIS, AND (2)
       THE EXPIRATION OR TERMINATION OF ANY APPLICABLE WAITING PERIOD UNDER  THE
       HART-SCOTT-RODINO  ANTITRUST IMPROVEMENTS  ACT OF  1976, AS  AMENDED. SEE
       "THE TENDER OFFER -- 13. CERTAIN CONDITIONS OF THE OFFER" IN THE OFFER TO
       PURCHASE.
<PAGE>
    5.  Any brokerage  fees, commissions or stock  transfer taxes applicable  to
       the  sale of the  Shares to the  Purchaser pursuant to  the Offer will be
       paid by such Purchaser, except as otherwise provided in Instruction 6  of
       the Letter of Transmittal.
 
    If  you wish to have us tender any or all of your Shares, please so instruct
us by completing, executing, detaching and returning to us the instruction  form
set  forth below. An envelope to return  your instructions to us is enclosed. If
you authorize tender  of your Shares,  all such Shares  will be tendered  unless
otherwise specified on the instruction form set forth below.
 
    YOUR  INSTRUCTIONS SHOULD BE FORWARDED  TO US IN AMPLE  TIME TO PERMIT US TO
SUBMIT A TENDER ON  YOUR BEHALF BY  THE EXPIRATION OF THE  OFFER. THE OFFER  AND
WITHDRAWAL  RIGHTS EXPIRE AT  12:00 MIDNIGHT, NEW YORK  CITY TIME, ON WEDNESDAY,
MAY 1, 1996, UNLESS THE PURCHASER EXTENDS THE OFFER.
 
    The Offer is  not being made  to, nor will  tenders be accepted  from or  on
behalf  of, holders of the Shares in any jurisdiction in which the making of the
Offer or acceptance thereof  would not be  in compliance with  the laws of  such
jurisdiction. In those jurisdictions the laws of which require that the Offer be
made  by a licensed  broker or dealer, the  Offer shall be deemed  to be made on
behalf of  the Purchaser  by Goldman,  Sachs &  Co. or  one or  more  registered
brokers or dealers licensed under the laws of such jurisdiction.
<PAGE>
                          INSTRUCTIONS WITH RESPECT TO
                           OFFER TO PURCHASE FOR CASH
                             ALL OUTSTANDING SHARES
                    OF COMMON STOCK AND CLASS B COMMON STOCK
                                       OF
                                MEDISENSE, INC.
 
    The undersigned acknowledge(s) receipt of your letter and the enclosed Offer
to  Purchase dated April  4, 1996 and  the related Letter  of Transmittal (which
collectively constitute  the  "Offer")  in  connection with  the  offer  by  AAC
Acquisition,  Inc., a Massachusetts  corporation and wholly  owned subsidiary of
Abbott Laboratories, to purchase all of the outstanding shares of common  stock,
par  value $.01  per share and  Class B common  stock, par value  $.01 per share
(together, the "Shares").
 
    This will instruct you to tender  the number of Shares indicated below  held
by  you for the  account of the undersigned,  upon the terms  and subject to the
conditions set  forth  in  the Offer  to  Purchase  and the  related  Letter  of
Transmittal.
  Number(1) of Shares to be Tendered: __________ Shares of Common Stock
 
                                   __________ Shares of Class B Common Stock
 
  Account Number: ________________________________________________
 
  Dated: _________________, 1996
 
                                   SIGN HERE
 
  Signature(s):_______________________________________________________________
 
  Print Name(s):______________________________________________________________
 
  Print Address(es):__________________________________________________________
 
  Area Code and Telephone No.:________________________________________________
 
  Taxpayer ID No. or Social Security No.:_____________________________________
 
(1)Unless otherwise indicated, it will be assumed that all Shares held by us for
your account are to be tendered.

<PAGE>
GOLDMAN, SACHS & CO.
85 BROAD STREET
NEW YORK, NEW YORK 10004
 
                           OFFER TO PURCHASE FOR CASH
        ALL OUTSTANDING SHARES OF COMMON STOCK AND CLASS B COMMON STOCK
                                       OF
                                MEDISENSE, INC.
                                       AT
                              $45.00 NET PER SHARE
                                       BY
                             AAC ACQUISITION, INC.
                          A WHOLLY OWNED SUBSIDIARY OF
 
                              ABBOTT LABORATORIES
 
           THE OFFER AND WITHDRAWAL RIGHTS EXPIRE AT 12:00 MIDNIGHT,
  NEW YORK CITY TIME, ON WEDNESDAY, MAY 1, 1996, UNLESS THE OFFER IS EXTENDED.
 
                                                                   April 4, 1996
 
TO BROKERS, DEALERS, COMMERCIAL
 BANKS, TRUST COMPANIES AND OTHER NOMINEES:
 
    We have been appointed by AAC Acquisition, Inc., a Massachusetts corporation
and  wholly owned subsidiary of Abbott Laboratories (the "Purchaser"), to act as
Dealer Managers in connection with the Purchaser's offer to purchase all of  the
outstanding shares of Common Stock, $.01 par value per share, and Class B Common
Stock,  $.01 par value per share (together, the "Shares"), of MediSense, Inc., a
Massachusetts corporation  (the "Company"),  at  $45.00 per  Share, net  to  the
seller  in cash,  without interest  thereon, upon the  terms and  subject to the
conditions set forth in the Purchaser's  Offer to Purchase, dated April 4,  1996
(the  "Offer to Purchase") and the related Letter of Transmittal (which together
constitute the "Offer").
 
    THE OFFER  IS  SUBJECT TO  SEVERAL  CONDITIONS  CONTAINED IN  THE  OFFER  TO
PURCHASE  INCLUDING, AMONG OTHER THINGS (1) THERE BEING VALIDLY TENDERED AND NOT
PROPERLY WITHDRAWN PRIOR TO THE EXPIRATION OF THE OFFER A NUMBER OF SHARES WHICH
CONSTITUTES AT LEAST A MAJORITY  OF THE OUTSTANDING SHARES  OF THE COMPANY ON  A
FULLY  DILUTED BASIS,  AND (2) THE  EXPIRATION OR TERMINATION  OF ANY APPLICABLE
WAITING PERIOD UNDER THE HART-SCOTT-RODINO  ANTITRUST IMPROVEMENTS ACT OF  1976,
AS AMENDED. THE OFFER IS ALSO SUBJECT TO OTHER TERMS AND CONDITIONS CONTAINED IN
THE  OFFER TO PURCHASE. SEE  "THE TENDER OFFER --  13. CERTAIN CONDITIONS OF THE
OFFER" IN THE OFFER TO PURCHASE.
 
    For your information and  for forwarding to your  clients for whom you  hold
Shares  registered in your name or in the name of your nominee, we are enclosing
the following documents:
 
       1.  Offer to Purchase, dated April 4, 1996.
 
       2.  Letter of  Transmittal to  tender Shares  for your  use and  for  the
           information   of   your   clients,  together   with   GUIDELINES  FOR
    CERTIFICATION OF  TAXPAYER  IDENTIFICATION  NUMBER ON  SUBSTITUTE  FORM  W-9
    providing  information  relating to  backup  federal income  tax withholding
    (facsimile copies  of  the Letter  of  Transmittal  may be  used  to  tender
    Shares);
 
       3.  Notice  of Guaranteed  Delivery for Shares  to be used  to accept the
           Offer if the certificates for the Shares being tendered and all other
    required documents are not immediately  available or cannot be delivered  to
    the  Depositary by the Expiration Date (as defined in the Offer to Purchase)
    or if  procedures  for  book-entry  transfer  cannot  be  completed  by  the
    Expiration Date;
<PAGE>
       4.  A  printed form of letter which may be sent to your clients for whose
           accounts you hold Shares  registered in your name  or in the name  of
    your  nominee, with space provided  for obtaining such clients' instructions
    with regard to the Offer; and
 
       5.  A letter to MediSense, Inc. stockholders.
 
    YOUR PROMPT ACTION  IS REQUESTED.  WE URGE YOU  TO CONTACT  YOUR CLIENTS  AS
PROMPTLY  AS POSSIBLE.  PLEASE NOTE  THAT THE  OFFER AND  WITHDRAWAL RIGHTS WILL
EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY TIME, ON WEDNESDAY, MAY 1, 1996,  UNLESS
THE OFFER IS EXTENDED.
 
    Upon the terms and subject to the conditions of the Offer (including, if the
Offer  is extended or amended, the terms and conditions of any such extension or
amendment), the Purchaser will accept for  payment and pay for the Shares  which
are  validly tendered prior to the  Expiration Date and not theretofore properly
withdrawn when, as  and if the  Purchaser gives  oral or written  notice to  the
Depositary  of the Purchaser's acceptance of such Shares for payment pursuant to
the Offer. Payment for the  Shares purchased pursuant to  the Offer will in  all
cases  be made only after  timely receipt by the  Depositary of certificates for
the Shares or timely confirmation of  a book-entry transfer of such Shares  into
the  Depositary's account  at The Depository  Trust Company  or the Philadelphia
Depository Trust Company, pursuant  to the procedures  described in "The  Tender
Offer--3.  Procedure for Tendering Shares" of  the Offer to Purchase, a properly
completed and duly executed Letter of Transmittal (or manually signed  facsimile
thereof) or an Agent's Message in connection with a book-entry transfer, and all
other documents required by the Letter of Transmittal.
 
    If  holders of Shares wish  to tender their Shares,  but it is impracticable
for them to forward their Share certificates or other required documents to  the
Depositary  on or prior to the Expiration  Date or to comply with the book-entry
transfer procedure on a timely basis, a tender may be effected by following  the
guaranteed  delivery procedures specified in "The Tender Offer--3. Procedure for
Tendering Shares" in the Offer to Purchase.
 
    The Purchasers will not pay any fees or commissions to any broker or  dealer
or  other person (other than to the Dealer Managers as described in the Offer to
Purchase) for  soliciting tenders  of  the Shares  pursuant  to the  Offer.  The
Purchasers  will,  however,  upon  request,  reimburse  you  for  reasonable and
necessary costs and  expenses incurred by  you in forwarding  materials to  your
customers.  The Purchaser will pay or cause  to be paid all stock transfer taxes
applicable to  its  purchase  of  Shares  pursuant  to  the  Offer,  subject  to
Instruction 6 of the Letter of Transmittal.
 
    Any inquiries you may have with respect to the Offer should be addressed to,
and  additional  copies of  the  enclosed materials  may  be obtained  from, the
Information Agent or the undersigned at the addresses and telephone numbers  set
forth on the back cover of the Offer to Purchase and the Letter of Transmittal.
 
                                          Very truly yours,
 
                                   GOLDMAN, SACHS & CO.
 
NOTHING  CONTAINED HEREIN OR  IN THE ENCLOSED DOCUMENTS  SHALL CONSTITUTE YOU OR
ANY PERSON AS  AN AGENT  OF THE  PURCHASER, THE  COMPANY, ANY  AFFILIATE OF  THE
COMPANY,  THE  DEALER  MANAGERS, THE  INFORMATION  AGENT OR  THE  DEPOSITARY, OR
AUTHORIZE YOU OR ANY OTHER PERSON TO  USE ANY DOCUMENT OR MAKE ANY STATEMENT  ON
BEHALF  OF ANY  OF THEM IN  CONNECTION WITH  THE OFFER OTHER  THAN THE DOCUMENTS
ENCLOSED HEREWITH AND THE STATEMENTS CONTAINED THEREIN.

<PAGE>
                         NOTICE OF GUARANTEED DELIVERY
                    (NOT TO BE USED FOR SIGNATURE GUARANTEE)
 
           TO TENDER SHARES OF COMMON STOCK AND CLASS B COMMON STOCK
                                       OF
                                MEDISENSE, INC.
             PURSUANT TO THE OFFER TO PURCHASE DATED APRIL 4, 1996
 
                                       OF
 
                             AAC ACQUISITION, INC.
 
                          A WHOLLY OWNED SUBSIDIARY OF
 
                              ABBOTT LABORATORIES
 
    This  Notice of Guaranteed Delivery, or  one substantially equivalent to the
attached form,  must be  used to  accept the  Offer (as  defined below)  if  (i)
certificates  for  shares  of Common  Stock,  par  value $.01  per  share and/or
certificates for  shares of  Class B  Common  Stock, par  value $.01  per  share
(together, the "Shares"), of MediSense, Inc. and all other documents required by
the  Letter  of  Transmittal  cannot  be  delivered  to  the  Depositary  by the
expiration of  the Offer  (as defined  in the  Offer to  Purchase) or  (ii)  the
procedures  for delivery of book-entry transfer  cannot be completed on a timely
basis. This Notice of Guaranteed  Delivery may be delivered  by hand or sent  by
facsimile  transmission or mail to  the Depositary. See "The  Tender Offer -- 3.
Procedure for Tendering Shares" in the Offer to Purchase.
 
                        THE DEPOSITARY FOR THE OFFER IS:
 
                       The First National Bank of Boston
 
<TABLE>
<S>                            <C>                            <C>
                                       BY FACSIMILE                     BY HAND:
          BY MAIL:                     TRANSMISSION:            BancBoston Trust Company
Shareholder Services Division   (for Eligible Institutions             of New York
        P.O. Box 1889                      Only)                55 Broadway, Third Floor
     Mail Stop 45-02-53               (617) 575-2232               New York, New York
 Boston, Massachusetts 02105          (617) 575-2233              BY OVERNIGHT COURIER:
       (800) 730-4001              CONFIRM FACSIMILE BY          The First National Bank
                                        TELEPHONE:                      of Boston
                                  (For Confirmation Only)     Shareholder Services Division
                                       (800)730-4001                150 Royall Street
                                                                   Mail Stop: 45-02-53
                                                               Canton, Massachusetts 02021
</TABLE>
 
    DELIVERY OF THIS NOTICE OF GUARANTEED  DELIVERY TO AN ADDRESS OTHER THAN  AS
SET  FORTH ABOVE OR TRANSMISSION OF INSTRUCTIONS VIA A FACSIMILE TRANSMISSION TO
A NUMBER OTHER THAN AS SET FORTH ABOVE DOES NOT CONSTITUTE A VALID DELIVERY.
 
    This  Notice  of  Guaranteed  Delivery  is  not  to  be  used  to  guarantee
signatures.  If  a  signature of  a  Letter  of Transmittal  is  required  to be
guaranteed by an  "Eligible Institution"  under the  instructions thereto,  such
signature  guarantee  must  appear  in  the  applicable  space  provided  in the
signature box on the Letter of Transmittal.
<PAGE>
Ladies and Gentlemen:
 
    The undersigned hereby tenders to  AAC Acquisition, Inc. (the  "Purchaser"),
upon  the terms and subject to the conditions set forth in the Offer to Purchase
dated April  4, 1996  and  the related  Letter  of Transmittal  (which  together
constitute  the  Offer), receipt  of which  is  hereby acknowledged,  the number
(indicated below) of Shares  pursuant to the  guaranteed delivery procedure  set
forth in "The Tender Offer -- 3. Procedure for Tendering Shares" of the Offer to
Purchase.
 
<TABLE>
<S>                                        <C>           <C>
Number of Shares being tendered hereby:    ------------  Shares of Common Stock
 
                                                         Shares of Class B Common Stock
                                           ------------
</TABLE>
 
<TABLE>
<S>                                            <C>
Certificate No(s).                                                                SIGN HERE:
(if available):                                 --------------------------------------------
- --------------------------------------------                                  (SIGNATURE(S))
If Shares will be tendered by book-entry       ---------------------------------------------
transfer:                                                        (NAME(S) OF RECORD HOLDERS)
Name of Tendering Institution                                                 (PLEASE PRINT)
Account No. at                                 ---------------------------------------------
/ / The Depository Trust Company                                                   (ADDRESS)
/ / Philadelphia Depository Trust Company      ---------------------------------------------
                                                                                  (ZIP CODE)
                                               ---------------------------------------------
                                                               (AREA CODE AND TELEPHONE NO.)
</TABLE>
 
                                   GUARANTEE
                    (NOT TO BE USED FOR SIGNATURE GUARANTEE)
 
    The  undersigned,  a  firm  which  is  a  member  of  a  registered national
securities exchange or the National Association of Securities Dealers, Inc.,  or
a  commercial bank or  trust company having  an office, branch  or agency in the
United States, hereby (a) represents that the above named person(s) "own(s)" the
Shares tendered hereby  within the meaning  of Rule 14e-4  under the  Securities
Exchange  Act of 1934, as amended, (b) represents that such tender complies with
Rule 14e-4 and (c) guarantees to  deliver to the Depositary the Shares  tendered
hereby,  together  with  a properly  completed  and duly  executed  Letter(s) of
Transmittal (or facsimile(s) thereof)  or an Agent's Message  as defined in  the
Offer  to Purchase in the case of  a book-entry delivery, and any other required
documents, all within five Nasdaq Stock Market trading days of the date hereof.
 
<TABLE>
<S>                                                       <C>
- --------------------------------------------               -------------------------------------------------------
 (NAME OF FIRM)                                                                             (AUTHORIZED SIGNATURE)
 
- -------------------------------------------------------    -------------------------------------------------------
 (ADDRESS)                                                                                                  (NAME)
 
- -------------------------------------------------------    -------------------------------------------------------
 (ZIP CODE)                                                                                                (TITLE)
 
- -------------------------------------------------------
 (AREA CODE AND TELEPHONE NO.)
 
Dated: , 1996.
</TABLE>
 
                 DO NOT SEND STOCK CERTIFICATES WITH THIS FORM.
      YOUR STOCK CERTIFICATES MUST BE SENT WITH THE LETTER OF TRANSMITTAL.

<PAGE>
            GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                         NUMBER ON SUBSTITUTE FORM W-9

GUIDELINES  FOR  DETERMINING  THE  PROPER  IDENTIFICATION  NUMBER  TO  GIVE  THE
PAYOR--Social Security numbers have nine digits separated by two hyphens:  i.e.
000-00-0000.  Employer identification numbers have nine digits separated by only
one hyphen: i.e. 00-0000000. The table  below will help determine the number  to
give the payor.
<TABLE>
<CAPTION>
- ------------------------------------------------------
                                     GIVE THE
                                     SOCIAL SECURITY
FOR THIS TYPE OF ACCOUNT:            NUMBER OF--
- ------------------------------------------------------
<C>  <S>                             <C>
 1.  An individual's account         The individual
 2.  Two or more individuals (joint  The actual owner
     account)                        of the account or,
                                     if combined funds,
                                     the first
                                     individual on the
                                     account(1)
 3.  Custodian account of a minor    The minor(2)
     (Uniform Gift to Minors Act)
 4.  a. The usual revocable savings  The
        trust account (grantor is    grantor-trustee(1)
        also trustee)
     b. So-called trust account      The actual
        that is not a legal or       owner(1)
        valid trust under State law
 5.  Sole proprietorship account     The owner(3)
- ------------------------------------------------------
 
<CAPTION>
 ------------------------------------------------------
                                     GIVE THE EMPLOYER
                                     IDENTIFICATION
FOR THIS TYPE OF ACCOUNT:            NUMBER OF--
 ------------------------------------------------------
<C>  <S>                             <C>
 6.  A valid trust, estate, or       The legal entity
     pension trust                   (Do not furnish the
                                     identifying number
                                     of the personal
                                     representative or
                                     trustee unless the
                                     legal entity
                                     itself is not
                                     designated in the
                                     account title)(4)
 7.  Corporate account               The corporation
 8.  Association, club, religious,   The organization
     charitable, educational or
     other tax-exempt organization
 9.  Partnership account             The partnership
10.  A broker or registered nominee  The broker or
                                     nominee
11.  Account with the Department of  The public entity
     Agriculture in the name of a
     public entity (such as a State
     or local government, school
     district, or prison) that
     receives agricultural program
     payments
 ------------------------------------------------------
 
</TABLE>
 
(1)  List first and circle the name of the person whose number you furnish.
 
(2)  Circle the minor's name and furnish the minor's social security number.
 
(3)  Show the name of the owner.
 
(4)  List first  and circle  the name  of the valid trust,  estate, or  pension
     trust.
 
NOTE: If no name is circled when there is more than one name, the number will be
      considered to be that of the first name listed.


<PAGE>
            GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                       NUMBER (TIN) ON SUBSTITUTE FORM W-9
             (Section references are to the Internal Revenue Code)
 
                                     PAGE 2
 
NAME

If you are an individual, generally provide the name shown on your social 
security card. However, if you have changed your last name, for instance, due 
to marriage, without informing the Social Security Administration of the name 
change, please enter your first name and both the last name shown on your 
social security card and your new last name.

OBTAINING A NUMBER

If you don't have a taxpayer identification number ("TIN"), apply for one 
immediately. To apply, obtain Form SS-5, Application for a Social Security 
Number Card, or Form SS-4, Application for Employer Identification Number, at 
the local office of the Social Security Administration or the Internal 
Revenue Service (the "IRS").

PAYEES AND PAYMENTS EXEMPT FROM BACKUP WITHHOLDING
 
The following is a list of payees exempt from backup withholding and for 
which no information reporting is required. For interest and dividends, all 
listed payees are exempt except item (9). For broker transactions, payees 
listed in (1) through (13), and a person registered under the Investment 
Advisors Act of 1940 who regularly acts as a broker are exempt. Payments 
subject to reporting under sections 6041 and 6041A are generally exempt from 
backup withholding only if made to payees described in items (1) through (7), 
except that a corporation that provides medical and health care services or 
bills and collects payments for such services is not exempt from backup 
withholding or information reporting.

 (1) A corporation.
 
 (2) An organization exempt from tax under section 501(a), or an individual
     retirement plan ("IRA"), or a custodial account under section 403(b)(7).
 
 (3) The United States or any agencies or instrumentalities.
 
 (4) A state, the District of Columbia, a possession of the United States, or
     any of their political subdivisions or instrumentalities.
 
 (5) A foreign government or any of its political subdivisions

 (6) An international organization or any of its agencies or 
     instrumentalities.

 (7) A foreign central bank of issue.

 (8) A dealer in securities or commodities required to register in the U.S. 
     or a possession of the U.S.

 (9) A futures commission merchant registered with the Commodity Futures 
     Trading Commission.

(10) A real estate investment trust.

(11) An entity registered at all times during the tax year under the 
     Investment Company Act of 1940.

(12) A common trust fund operated by a bank under section 584(a).

(13) A financial institution.

(14) A middleman known in the investment community as a nominee or listed in 
     the most recent publication of the American Society of Corporate 
     Secretaries, Inc. Nominee List.

(15) A trust exempt from tax under Section 664 or described in section 4947.


Payments of dividends generally not subject to backup withholding also 
include the following:

  -  Payments to nonresident aliens subject to withholding under section 1441.

  -  Payments to partnerships not engaged in a trade or business in the U.S. 
     and which have at least one nonresident partner.

  -  Payments made by certain foreign organizations.

Payments of interest generally not subject to backup withholding include the 
following:

  -  Payments of interest on obligations issued by individuals.

NOTE: YOU MAY BE SUBJECT TO BACKUP WITHHOLDING IF THIS INTEREST IS $600 OR 
MORE AND IS PAID IN THE COURSE OF THE PAYOR'S TRADE OR BUSINESS AND YOU HAVE 
NOT PROVIDED YOUR CORRECT TIN TO THE PAYOR.

  -  Payments of tax-exempt interest (including exempt-interest dividends 
     under section 852).

  -  Payments described in section 6049(b)(5) to nonresident aliens.

  -  Payments on tax-free covenant bonds under section 1451.

  -  Payments made by certain foreign organizations.

  -  Mortgage interest paid by you.

     Payments that are not subject to information reporting are also not 
subject to backup withholding. For details, see sections 6041, 6041A(a), 
6042, 6044, 6045, 6049, 6050A, and 6050N, and the regulations under those 
sections.

     PRIVACY ACT NOTICE. -- Section 6109 requires you to furnish your correct 
TIN to persons who must file information returns with the IRS to report 
interest, dividends, and certain other income paid to you, mortgage interest 
you paid, the acquisition or abandonment of secured property, or 
contributions you made to an IRA. The IRS uses the numbers for identification 
purposes and to help verify the accuracy of your tax return. You must provide 
your TIN whether or not you are qualified to file a tax return. Payors must 
generally withhold 31% of taxable interest, dividend, and certain other 
payments to a payee who does not furnish a TIN to a payor. Certain penalties 
may also apply.

PENALTIES

(1) FAILURE TO FURNISH TIN. -- If you fail to furnish your correct TIN to a 
payor, you are subject to a penalty of $50 for each such failure unless your 
failure is due to reasonable cause and not to willful neglect.

(2) CIVIL PENALTY FOR FALSE INFORMATION WITH RESPECT TO WITHHOLDING. -- If 
you make a false statement with no reasonable basis that results in no 
imposition of backup withholding, you are subject to a penalty of $500.

(3) CRIMINAL PENALTY FOR FALSIFYING INFORMATION. -- Willfully falsifying 
certifications or affirmations may subject you to criminal penalties 
including fines and/or imprisonment.

                          FOR ADDITIONAL INFORMATION
                    CONTACT YOUR TAX CONSULTANT OR THE IRS


<PAGE>

THIS ANNOUNCEMENT IS NEITHER AN OFFER TO PURCHASE NOR A SOLICITATION OF AN OFFER
TO SELL SHARES. THE OFFER IS MADE SOLELY BY THE OFFER TO PURCHASE DATED APRIL 4,
 1996 AND THE RELATED LETTER OF TRANSMITTAL, AND IS BEING MADE TO ALL HOLDERS
  OF SHARES, EXCEPT IN ANY JURISDICTION WHERE THE MAKING OF SUCH WOULD BE
  ILLEGAL.  THE PURCHASER IS NOT AWARE OF ANY STATE IN WHICH THE MAKING OF
   THE OFFER IS PROHIBITED BY ADMINISTRATIVE OR JUDICIAL ACTION PURSUANT TO
    A STATE STATUTE. IF THE PURCHASER BECOMES AWARE OF ANY STATE WHERE THE
     MAKING OF THE OFFER IS SO PROHIBITED, THE PURCHASER WILL MAKE A GOOD
      FAITH EFFORT TO COMPLY WITH ANY SUCH STATUTE OR SEEK TO HAVE SUCH
       STATUTE DECLARED INAPPLICABLE TO THE OFFER. IF, AFTER SUCH GOOD
        FAITH EFFORT, THE PURCHASER CANNOT COMPLY WITH ANY APPLICABLE
         STATUTE, THE OFFER WILL NOT BE MADE TO (NOR WILL TENDERS BE
          ACCEPTED FROM OR ON BEHALF OF) HOLDERS OF SHARES IN SUCH
           STATE.  IN ANY JURISDICTIONS, THE SECURITIES LAWS OR BLUE
            SKY LAWS OF WHICH REQUIRE THE OFFER TO BE MADE BY A
             LICENSED BROKER OR DEALER, THE OFFER SHALL BE DEEMED
              TO BE MADE ON BEHALF OF THE PURCHASER, IF AT ALL, BY
               GOLDMAN, SACHS & CO., AS DEALER MANAGERS, OR ONE
                OR MORE  REGISTERED BROKERS OR DEALERS THAT
                 ARE LICENSED UNDER THE LAWS OF, AND REPRESENT
                  THE STOCKHOLDER RESIDING IN, SUCH JURISDICTION.

                        NOTICE OF OFFER TO PURCHASE FOR CASH
                             ALL OUTSTANDING SHARES OF
                       COMMON STOCK AND CLASS B COMMON STOCK

                                         OF

                                  MEDISENSE, INC.

                                         AT

                                $45.00 NET PER SHARE

                                         BY

                               AAC ACQUISITION, INC.

                            A WHOLLY OWNED SUBSIDIARY OF

                                ABBOTT LABORATORIES

AAC Acquisition, Inc., a Massachusetts corporation (the "Purchaser"), which 
is wholly owned by Abbott Laboratories, an Illinois corporation ("Parent"), 
is offering to purchase any and all shares of common stock, par value $.01 
per share, and Class B common stock, par value $.01 per share (together, the 
"Shares"), of MediSense, Inc., a Massachusetts corporation (the "Company"), 
at $45.00 per Share (the "Offer Price"), net to the seller in cash, without 
interest thereon, upon the terms and subject to the conditions set forth in 
the Offer to Purchase dated April 4, 1996 (the "Offer to Purchase") and in 
the related Letter of Transmittal (which, together, constitute the "Offer"). 
- --------------------------------------------------------------------------------
   THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK    
 TIME, ON WEDNESDAY, MAY 1, 1996 (THE "EXPIRATION DATE"), UNLESS THE OFFER    
 IS EXTENDED. 
- --------------------------------------------------------------------------------

    THE OFFER IS CONDITIONED, AMONG OTHER THINGS, UPON SATISFACTION, IN
PURCHASER'S SOLE DISCRETION, OF THE FOLLOWING CONDITIONS: (1) THE CONDITION (THE
"MINIMUM CONDITION") THAT THERE SHALL HAVE BEEN VALIDLY TENDERED AND NOT
PROPERLY WITHDRAWN ON OR PRIOR TO THE EXPIRATION DATE OF THE OFFER A NUMBER OF
SHARES REPRESENTING NOT LESS THAN A MAJORITY OF THE COMPANY'S OUTSTANDING VOTING
POWER ON A FULLY DILUTED BASIS ON THE DATE OF PURCHASE, AND (2) THE EXPIRATION
OR TERMINATION OF ANY APPLICABLE WAITING PERIOD UNDER THE HART-SCOTT-RODINO
ANTITRUST IMPROVEMENTS ACT OF 1976, AS AMENDED.


<PAGE>

CERTAIN OTHER CONDITIONS TO THE OFFER ARE DESCRIBED IN "THE TENDER 
OFFER--SECTION 13. CERTAIN CONDITIONS OF THE OFFER" IN THE OFFER TO PURCHASE. 
 THE PURCHASER ESTIMATES THAT APPROXIMATELY 9,740,000 SHARES WILL NEED TO BE 
VALIDLY TENDERED (AND NOT VALIDLY WITHDRAWN) TO SATISFY THE MINIMUM CONDITION.

    The Offer is being made in connection with an Agreement and Plan of Merger
(the "Merger Agreement") dated as of March 29, 1996 among the Company,
Purchaser and Parent.  Pursuant to the Merger Agreement, and on the terms and
subject to the conditions set forth therein, Purchaser will merge with and into
the Company (the "Merger"), with the Company to be the surviving corporation in
such Merger, and each outstanding Share of the Company (other than Shares held
by Parent, Purchaser or the Company, which will be cancelled, and Shares held by
stockholders who properly exercise appraisal rights under Massachusetts law)
will be converted into the right to receive an amount equal to the Offer Price.
Following the consummation of the Merger, the Company will continue as the
surviving corporation and will be a wholly owned subsidiary of Parent.  At
Purchaser's option, the Merger may be alternatively structured so that any
direct or indirect subsidiary of Parent is merged with and into the Company.
See "The Tender Offer--Section 10. Purpose of the Offer; the Merger Agreement"
in the Offer to Purchase.

    THE BOARD OF DIRECTORS OF THE COMPANY UNANIMOUSLY HAS DETERMINED THAT THE 
OFFER AND THE MERGER, TAKEN TOGETHER, ARE FAIR TO, AND IN THE BEST INTERESTS 
OF, THE COMPANY AND ITS STOCKHOLDERS AND UNANIMOUSLY HAS APPROVED THE OFFER 
AND THE MERGER AND RECOMMENDS THAT STOCKHOLDERS OF THE COMPANY ACCEPT THE 
OFFER AND TENDER THEIR SHARES. SEE "RECOMMENDATION OF THE COMPANY'S BOARD OF 
DIRECTORS" IN THE OFFER TO PURCHASE.

    For purposes of the Offer, the Purchaser will be deemed to have accepted 
for payment, and thereby purchased, Shares validly tendered and not validly 
withdrawn, as, if and when the Purchaser gives oral or written notice to The 
First National Bank of Boston (the "Depositary") of the Purchaser's 
acceptance of such Shares for payment pursuant to the Offer. In all cases, 
upon the terms and subject to the conditions of the Offer, payment for Shares 
purchased pursuant to the Offer will be made by deposit of the purchase price 
therefor with the Depositary, which will act as agent for tendering 
stockholders for the purpose of receiving payments from the Purchaser and 
transmitting such payments to validly tendering stockholders. Under no 
circumstances will interest on the purchase price for Shares be paid by the 
Purchaser by reason of any delay in making such payment. In all cases, 
payment for Shares accepted for payment pursuant to the Offer will be made 
only after timely receipt by the Depositary of (a) certificates for such 
Shares ("Share Certificates") or timely confirmation of the book-entry 
transfer of such Shares into the Depositary's account at The Depository Trust 
Company or the Philadelphia Depository Trust Company (collectively, the 
"Book-Entry Transfer Facilities"), pursuant to the procedures set forth in 
"The Tender Offer--Section 3. Procedures for Tendering Shares" in the Offer 
to Purchase, (b) the Letter of Transmittal (or facsimile thereof) properly 
completed and duly executed with any required signature guarantees (or, 
alternatively, an Agent's Message, as set forth in the Offer to Purchase) and 
(c) any other documents required by the Letter of Transmittal.

    The term "Expiration Date" means 12:00 Midnight, New York City time, on
Wednesday, May 1, 1996, unless and until the Purchaser, in its sole discretion,
shall have extended the period of time for which the Offer is open, in which
event the term "Expiration Date" shall mean the latest time and date at which
the Offer, as so extended by the Purchaser, shall expire. The Purchaser
expressly reserves the right, in its sole discretion, at any time and from time
to time, to extend the period during which the Offer is open for any reason,
including the nonsatisfaction of any of the conditions specified in the Offer
to Purchase, by giving oral or written notice of such extension to the
Depositary, followed as promptly as practicable by public announcement no later
than 9:00 A.M., New York City time, on the next business day after the
previously scheduled Expiration Date. During any such extension, all Shares
previously tendered and not withdrawn will remain subject to the Offer, subject
to the right of tendering stockholders to withdraw such stockholder's Shares.

    The Purchaser's acceptance for payment of Shares tendered pursuant to any
one of the procedures described in the Offer to Purchase and in the Letter of
Transmittal will constitute a binding agreement between the tendering
stockholder and the Purchaser upon the terms and subject to the conditions of
the Offer. Except as otherwise provided in "The Tender Offer--Section 4.
Withdrawal Rights" in the Offer to Purchase, tenders of Shares made pursuant to
the Offer are irrevocable. Shares tendered pursuant to the Offer may be
withdrawn at any time on or prior to the Expiration Date and, unless theretofore
accepted for payment as provided herein, may also be withdrawn at any time
after June 2, 1996. For a withdrawal to be effective, a written or
facsimile transmission notice of withdrawal must be timely received by the
Depositary at its address set forth on the back cover of the Offer to Purchase.
Any such notice of withdrawal must specify the name of the person who tendered
the Shares to be withdrawn, and if Share Certificates have been tendered, the
name of the registered holder of the Shares as set forth in the Share
Certificate, if different from that of the person who tendered such Shares. If
Share Certificates have been delivered or otherwise identified to the
Depositary, then prior to the physical release of such certificates, the
tendering stockholder must submit the serial numbers shown on the particular
certificates evidencing the Shares to be withdrawn and the signature on the
notice of withdrawal must be guaranteed by an Eligible Institution (as defined
in the Offer to Purchase), except in the case of Shares tendered for the account
of an Eligible Institution. If Shares have been tendered pursuant to the
procedures for book-entry transfer as set forth in "The Tender Offer--Section 3.
Procedure for Tendering Shares" in the Offer to Purchase, the notice of
withdrawal must specify the name and number of the account at the appropriate
Book-Entry Transfer Facility to be credited with the withdrawn Shares, in which
case a notice of withdrawal will be effective if a written or facsimile
transmission notice of withdrawal is timely received by the Depositary at its
address set forth on the back cover of the Offer to Purchase. Withdrawals of
Shares may not be rescinded. Any Shares properly withdrawn will be deemed not
validly tendered for purposes of the Offer, but may be retendered at any
subsequent time prior to the Expiration Date by following any of the procedures
described in "The Tender Offer--Section 3. Procedure for Tendering Shares" in
the Offer to Purchase. All questions as to the form and validity (including time
of receipt) of any notices of withdrawal will be determined by the Purchaser, in
its sole discretion whose determination will be final and binding.

    The information required to be disclosed by Rule 14d-6(e)(1) of the
General Rules and Regulations under the Securities Exchange Act of 1934, as
amended, is contained in the Offer to Purchase and is incorporated herein by
reference.

    The Company has provided the Company's stockholder list and security
position listings to the Purchaser for the purpose of disseminating the Offer to
stockholders. The Offer to Purchase and the related Letter of Transmittal and,
if required, other relevant materials will be mailed to stockholders whose names
appear on the Company's stockholder list and will be furnished for subsequent
transmittal to beneficial owners of Shares,


                                      -2-

<PAGE>

to brokers, dealers, commercial banks, trust companies and similar persons whose
names, or the names of whose nominees, appear on the stockholder list or, if
applicable, who are listed as participants in a clearing agency's security
listing.

    STOCKHOLDERS ARE URGED TO READ THE OFFER TO PURCHASE AND THE RELATED LETTER
OF TRANSMITTAL CAREFULLY BEFORE DECIDING WHETHER TO TENDER THEIR SHARES.

    Questions and requests for assistance may be directed to the Information 
Agent or the Dealer Managers at the addresses and telephone numbers set forth 
below. Requests for copies of the Offer to Purchase and the related Letter of 
Transmittal and other tender Offer materials may be directed to the 
Information Agent or the Dealer Managers or brokers, dealers, commercial 
banks and trust companies and such materials will be furnished promptly at 
the Purchaser's expense. The Purchaser will not pay any fees or commissions 
to brokers, dealers, or other persons (other than the Information Agent and 
the Dealer Managers) for soliciting tenders of Shares pursuant to the Offer.

                      THE INFORMATION AGENT FOR THE OFFER IS:

                                     GEORGESON
                                   & COMPANY INC.
                                 ------------------

                                 Wall Street Plaza
                              New York, New York 10005
                   Banks and Brokers call collect (212) 440-9800

                     ALL OTHERS CALL TOLL FREE: 1-800-223-2064

April 4, 1996

                      THE DEALER MANAGERS FOR THE OFFER ARE:

                              GOLDMAN, SACHS & CO.
                                85 BROAD STREET
                            NEW YORK, NEW YORK 10004
                    IN NEW YORK STATE: (212) 902-1000 (COLLECT)
                      OTHER AREAS: (800) 323-5678 (TOLL FREE)


                                       -3-

<PAGE>


                   ABBOTT LABORATORIES TO ACQUIRE MEDISENSE, INC.

     Abbott Part, Ill., and Waltham, Ma., March 29, 1996 -- Abbott 
Laboratories (NYSE: ABT) and MediSense, Inc. (NASDAQ:MSNS) today announced 
that they have signed a definitive agreement through which Abbott will 
acquire MediSense, the biosensor technology leader in blood glucose 
self-testing systems for people with diabetes.

     Under the terms of the agreement, Abbott will make a tender offer to 
acquire 100 percent of the outstanding shares of MediSense for $45 per share, 
or an equity value of approximately $876 million. The Abbott and MediSense 
boards of directors have endorsed the offer. The tender offer is expected to 
be completed in approximately five weeks, subject to regulatory approvals and 
customary closing conditions. Following the tender offer, MediSense will be 
merged into a wholly-owned subsidiary of Abbott Laboratories, and each 
remaining MediSense shareholder will receive $45 per share in exchange for 
each MediSense share held.

     "We are extremely pleased to add MediSense's superior technology and 
outstanding people to our company," said Duane L. Burnham, chairman and chief 
executive officer of Abbott Laboratories. "MediSense fits very well with our 
diagnostics operations, and will create many opportunities for synergy with 
our other divisions as well."

     According to Miles D. White, senior vice president, diagnostics 
operations, the acquisition advances Abbott's interests in the glucose 
monitoring market. "This important strategic step, combined with other 
internal and external initiatives to secure industry-leading technology in 
glucose monitoring, will position Abbott very favorably in this market. In 
addition to providing immediate access to the fastest-growing segment of the 
diagnostics market, MediSense's research and development program will augment 
our existing work to develop and commercialize future non-invasive monitoring 
technologies," said White.

     "We are delighted to become a part of the world's leading diagnostics 
company," said Robert L. Coleman, Ph.D., president and chief executive 
officer of MediSense. "The combination of the two organizations will 
accelerate market growth and will ensure continued development and 
availability of therapies to improve the care of people with diabetes."

     MediSense manufactures products that allow people with diabetes to 
routinely measure blood glucose which is critical to diabetes management. The 
products are compact, easy-to-use home glucose meters and disposable 
single-use test strips. MediSense was the first company to develop a 
biosensor-based blood glucose self-testing system. MediSense's leading 
system, the Precision Q/ /I/ /D-TM-, provides accurate results, with less 
blood, faster than any competition product.

     The MediSense subsidiary of Abbott will continue to be located in 
Massachusetts, with Dr. Coleman remaining as president of the subsidiary. 
MediSense is a worldwide developer, manufacturer and marketer of blood 
glucose self-testing systems that enable people with diabetes to manage their 
disease more effectively. MediSense believes the convenience and simplicity 
of its products promote increased testing compliance by individual with 
diabetes and provide for more effective management of their condition.

     Abbott Laboratories is a diversified global manufacturer of health care 
products, employing 50,000 people researches, develops and markets 
pharmaceutical, diagnostic, nutritional and hospital products. In 1995, the 
company's sales and net earnings were $10.0 billion and $1.7 billion, 
respectively, with earnings per share of $2.12.

                                      ###

The Purchaser commenced the Offer on April 4, 1996.


<PAGE>
                                                                       EXHIBIT 3
 
                                                                   April 4, 1996
 
Dear Stockholder:
 
    We  are pleased to report  that, on March 29,  1996, MediSense, Inc. entered
into a merger  agreement with Abbott  Laboratories and one  of its  subsidiaries
that  provides for the acquisition  of MediSense by Abbott  at a price of $45.00
per share  in cash.  Under the  terms  of the  proposed transaction,  an  Abbott
subsidiary is today commencing a cash tender offer for all outstanding shares of
MediSense  common stock and class B common  stock at $45.00 per share. Following
the successful completion of the Abbott tender offer, the Abbott subsidiary will
be merged into MediSense and all shares not purchased in the Abbott tender offer
will be converted  into the right  to receive $45.00  per share in  cash in  the
merger.
 
    YOUR BOARD OF DIRECTORS HAS UNANIMOUSLY APPROVED THE ABBOTT TENDER OFFER AND
DETERMINED  THAT THE TERMS OF  THE TENDER OFFER AND  THE MERGER, TAKEN TOGETHER,
ARE FAIR  TO, AND  IN THE  BEST INTERESTS  OF, MEDISENSE  AND ITS  STOCKHOLDERS.
ACCORDINGLY,  THE BOARD OF  DIRECTORS UNANIMOUSLY RECOMMENDS  THAT ALL MEDISENSE
STOCKHOLDERS ACCEPT THE ABBOTT TENDER OFFER AND TENDER THEIR SHARES TO ABBOTT.
 
    In arriving  at its  recommendations, the  Board of  Directors gave  careful
consideration  to a  number of  factors. These  factors included  the opinion of
Alex. Brown & Sons Incorporated, financial advisors to MediSense, that the  cash
consideration  of  $45.00 per  share to  be  received by  MediSense stockholders
pursuant to the  Abbott tender offer  and the  merger is fair  from a  financial
point of view to such stockholders.
 
    Accompanying this letter is a copy of MediSense's
Solicitation/Recommendation  Statement  on  Schedule  14D-9.  Also  enclosed  is
Abbott's Offer  to  Purchase  and  related  materials,  including  a  Letter  of
Transmittal  for  use in  tendering shares.  We  urge you  to read  the enclosed
materials, including Alex.  Brown's fairness  opinion which is  attached to  the
Schedule 14D-9, carefully.
 
    The management and directors of MediSense thank you for the support you have
given the company.
 
                                          Sincerely,
 
                                          Richard C.E. Morgan
                                          CHAIRMAN OF THE BOARD
 
                                          Robert L. Coleman, Ph.D.
                                          PRESIDENT AND CHIEF EXECUTIVE OFFICER

<PAGE>

                                                                  EXECUTION COPY







                             AGREEMENT AND PLAN OF MERGER



                                        Among



                                   MEDISENSE, INC.,



                                 ABBOTT LABORATORIES


                                         and


                                AAC ACQUISITION, INC.



                              dated as of March 29, 1996

<PAGE>

                                  TABLE OF CONTENTS

                                                                        PAGE


                                      ARTICLE I
                                      THE OFFER. . . . . . . . . . . .    2

    Section 1.1    The Offer . . . . . . . . . . . . . . . . . . . . .    2
    Section 1.2    Company Action. . . . . . . . . . . . . . . . . . .    3
    Section 1.3    Boards of Directors and Committees;
                   Section 14(f) . . . . . . . . . . . . . . . . . . .    5

                                      ARTICLE II
                                      THE MERGER . . . . . . . . . . .    6

    Section 2.1    The Merger. . . . . . . . . . . . . . . . . . . . .    6
    Section 2.2    Effective Time; Closing . . . . . . . . . . . . . .    6
    Section 2.3    Effects of the Merger; Subsequent
                   Actions . . . . . . . . . . . . . . . . . . . . . .    6
    Section 2.4    Articles of Organization; By-Laws . . . . . . . . .    7
    Section 2.5    Directors . . . . . . . . . . . . . . . . . . . . .    7
    Section 2.6    Officers. . . . . . . . . . . . . . . . . . . . . .    7
    Section 2.7    Conversion of Securities. . . . . . . . . . . . . .    7
    Section 2.8    Stock Options . . . . . . . . . . . . . . . . . . .    8
    Section 2.9    Company Employee Stock Purchase Plan. . . . . . . .    8
    Section 2.10   Stockholders' Meeting . . . . . . . . . . . . . . .    8

                                     ARTICLE III
                        DISSENTING SHARES; EXCHANGE OF SHARES. . . . .    9

    Section 3.1    Dissenting Shares . . . . . . . . . . . . . . . .     10
    Section 3.2    Exchange of Certificates. . . . . . . . . . . . .     10

                                      ARTICLE IV
                    REPRESENTATIONS AND WARRANTIES OF THE COMPANY. .     11

    Section 4.1    Organization and Qualification;
                   Subsidiaries. . . . . . . . . . . . . . . . . . .     12
    Section 4.2    Capitalization of the Company and
                   Its Subsidiaries. . . . . . . . . . . . . . . . .     13
    Section 4.3    Authority Relative to This Agreement. . . . . . .     13
    Section 4.4    Non-Contravention; Required Filings
                   and Consents... . . . . . . . . . . . . . . . . .     14
    Section 4.5    SEC Reports.... . . . . . . . . . . . . . . . . .     15
    Section 4.6    Absence of Certain Changes; Derivatives . . . . .     16
    Section 4.7    Schedule 14D-9; Offer Documents;
                   Proxy Statement . . . . . . . . . . . . . . . . .     16
    Section 4.8    Finder's Fee... . . . . . . . . . . . . . . . . .     17
    Section 4.9    Absence of Litigation . . . . . . . . . . . . . .     17
    Section 4.10   Taxes . . . . . . . . . . . . . . . . . . . . . .     17

<PAGE>

    Section 4.11   Employee Benefits . . . . . . . . . . . . . . . .     19
    Section 4.12   Compliance. . . . . . . . . . . . . . . . . . . .     20
    Section 4.13   Environmental Matters . . . . . . . . . . . . . .     21
    Section 4.14   Intellectual Property . . . . . . . . . . . . . .     23
    Section 4.15   Insurance . . . . . . . . . . . . . . . . . . . .     24
    Section 4.16   Properties. . . . . . . . . . . . . . . . . . . .     24
    Section 4.18   Labor Matters . . . . . . . . . . . . . . . . . .     25
    Section 4.19   Voting Requirements . . . . . . . . . . . . . . .     26
    Section 4.20   State Takeover Laws . . . . . . . . . . . . . . .     26

                                      ARTICLE V
                      REPRESENTATIONS AND WARRANTIES OF PARENT
                                   AND ACQUISITION . . . . . . . . .     26

    Section 5.1    Organization. . . . . . . . . . . . . . . . . . .     26
    Section 5.2    Authority Relative to this Agreement. . . . . . .     27
    Section 5.3    Non-Contravention; Required Filings
                   and Consents. . . . . . . . . . . . . . . . . . .     27

    Section 5.4    Offer Documents; Schedule 14D-9;
                   Proxy Statement . . . . . . . . . . . . . . . . .     28
    Section 5.5    No Prior Activities . . . . . . . . . . . . . . .     28
    Section 5.6    Financing . . . . . . . . . . . . . . . . . . . .     29

                                      ARTICLE VI
                                      COVENANTS. . . . . . . . . . .     29

    Section 6.1    Conduct of Business of the Company. . . . . . . .     29
    Section 6.2    Access to Information . . . . . . . . . . . . . .     31
    Section 6.3    Reasonable Best Efforts . . . . . . . . . . . . .     32
    Section 6.4    Public Announcements. . . . . . . . . . . . . . .     32
    Section 6.5    Indemnification . . . . . . . . . . . . . . . . .     33
    Section 6.6    Notification of Certain Matters . . . . . . . . .     33
    Section 6.7    Termination of Stock Plans. . . . . . . . . . . .     34
    Section 6.8    No Solicitation34

                                     ARTICLE VII
                       CONDITIONS TO CONSUMMATION OF THE MERGER. . .     35

    Section 7.1    Conditions to Each Party's Obligation to
                   Effect the Merger . . . . . . . . . . . . . . . .     35

                                     ARTICLE VIII
                       TERMINATION; EXPENSES; AMENDMENT; WAIVER. . .     35

    Section 8.1    Termination . . . . . . . . . . . . . . . . . . .     35
    Section 8.2    Effect of Termination . . . . . . . . . . . . . .     37
    Section 8.3    Fees and Expenses . . . . . . . . . . . . . . . .     38
    Section 8.4    Amendment . . . . . . . . . . . . . . . . . . . .     38
    Section 8.5    Extension; Waiver . . . . . . . . . . . . . . . .     38

<PAGE>

                                      ARTICLE IX
                                    MISCELLANEOUS. . . . . . . . . .     38

    Section 9.1    Nonsurvival of Representations
                   and Warranties. . . . . . . . . . . . . . . . . .     38
    Section 9.2    Entire Agreement; Assignment. . . . . . . . . . .     38
    Section 9.3    Notices . . . . . . . . . . . . . . . . . . . . .     39
    Section 9.4    Governing Law . . . . . . . . . . . . . . . . . .     40
    Section 9.5    Parties in Interest . . . . . . . . . . . . . . .     40
    Section 9.6    Specific Performance. . . . . . . . . . . . . . .     40
    Section 9.7    Severability. . . . . . . . . . . . . . . . . . .     40
    Section 9.8    Descriptive Headings. . . . . . . . . . . . . . .     40
    Section 9.9    Certain Definitions . . . . . . . . . . . . . . .     40
    Section 9.10   Counterparts. . . . . . . . . . . . . . . . . . .     41

<PAGE>

                                ANNEXES AND SCHEDULES



Annex A - Offer Conditions
Annex B - Press Release

Schedule 4.6
Schedule 4.9
Schedule 4.11
Schedule 4.14
Schedule 4.17
Schedule 4.18


<PAGE>

                             AGREEMENT AND PLAN OF MERGER


    THIS AGREEMENT AND PLAN OF MERGER, dated as of March 29, 1996, is among
MediSense, Inc., a Massachusetts corporation (the "Company"), Abbott
Laboratories, an Illinois corporation ("Parent") and AAC Acquisition, Inc., a
Massachusetts corporation and a wholly owned subsidiary of Parent
("Acquisition").

    WHEREAS, the Board of Directors of Parent, Acquisition and the Company have
each approved the acquisition of the Company by Parent upon the terms and
subject to the conditions set forth in this Agreement;

    WHEREAS, in furtherance thereof, it is proposed that Acquisition shall make
a tender offer to acquire all outstanding shares of common stock, par value
$0.01 per share, of the Company (the "Common Stock") and all outstanding shares
of class B common stock, par value $0.01 per share,of the Company (the "Class B
Common Stock" and together with the Common Stock, the "Shares"), for a cash
amount of $45.00 per Share (such amount, or any greater amount per Share paid
pursuant to the tender offer, being hereinafter referred to as the "Per Share
Amount") in accordance with the terms and subject to the conditions provided for
herein (the "Offer");

    WHEREAS, the Board of Directors of the Company (the "Board") has (i)
determined that the consideration to be paid for each Share in the Offer and the
Merger (as defined below) is fair to and in the best interests of the
stockholders of the Company and (ii) approved this Agreement and the
transactions contemplated hereby and resolved to recommend acceptance of the
Offer and approval and adoption of this Agreement by the stockholders of the
Company; and

    WHEREAS, the Boards of Directors of Parent and Acquisition have each
approved the merger (the "Merger") of Acquisition with and into the Company
following the Offer in accordance with the General Laws of the Commonwealth of
Massachusetts ("Massachusetts Law") upon the terms and subject to the conditions
set forth herein.

    NOW, THEREFORE, in consideration of the foregoing and the mutual covenants
and agreements herein contained, and intending to be legally bound hereby, the
Company, Parent and Acquisition hereby agree as follows;

<PAGE>

                                      ARTICLE I

                                      THE OFFER

    Section 1.1    THE OFFER.  (a)  Provided that this Agreement shall not have
been terminated in accordance with Section 8.1, as promptly as practicable, but
in no event later than the fifth business day following the public announcement
of the terms of this Agreement, Acquisition shall commence the Offer.  The
obligation of Acquisition to accept for payment and pay for Shares tendered
pursuant to the Offer shall be subject to the condition that a number of Shares
representing not less than a majority of the Company's outstanding voting power
(assuming the exercise of all outstanding options to purchase shares of Common
Stock and the conversion of all outstanding shares of Class B Common Stock into
Common Stock) shall have been validly tendered and not withdrawn prior to the
expiration date of the Offer (the "Minimum Condition"), and the obligation of
Acquisition to accept for payment and pay for Shares tendered pursuant to the
Offer shall be subject to the other conditions set forth in Annex A hereto.  It
is agreed that the Minimum Condition and the other conditions set forth in Annex
A hereto are for the sole benefit of Acquisition and may be asserted by
Acquisition regardless of the circumstances giving rise to any such condition
unless Parent, Acquisition or their affiliates shall have caused the
circumstances giving rise to such condition.  Acquisition expressly reserves the
right in its sole discretion to waive, in whole or in part, at any time or from
time to time, any such condition (other than the Minimum Condition, which may
not be waived without the prior written consent of the Company), to increase the
price per Share payable in the Offer or to make any other changes in the terms
and conditions of the Offer; PROVIDED that, unless previously approved by the
Company in writing, no change may be made that decreases the price per Share
payable in the Offer, changes the form of consideration payable in the Offer,
reduces the maximum number of Shares to be purchased in the Offer or imposes
conditions to the Offer in addition to those set forth in Annex A hereto.
Acquisition covenants and agrees that, subject to the conditions of the Offer
set forth in Annex A hereto, Acquisition shall accept for payment and pay for
Shares which have been validly tendered and not withdrawn pursuant to the Offer
as soon as it is permitted to do so under applicable law; PROVIDED that, if the
number of Shares that have been validly tendered and not withdrawn represent
less than 90% of the Shares outstanding on a fully diluted basis, Acquisition
may extend the Offer up to the tenth business day following the date on which
all conditions to the Offer shall first have been satisfied or waived.  The Per
Share Amount payable in the Offer shall be paid net to the seller in cash, upon
the terms and subject to the conditions of the Offer.  Acquisition agrees that


                                         -2-

<PAGE>

if all conditions set forth in Annex A are not satisfied on the initial
expiration date of the Offer, Acquisition shall extend (and re-extend) the Offer
through June 30, 1996 to provide time to satisfy such conditions; PROVIDED that,
if Acquisition shall not have purchased Shares pursuant to the Offer prior to
June 30, 1996 as the result of the receipt by the Company of an Acquisition
Proposal (as defined below) or as a result a failure of the applicable waiting
period under the HSR Act (as defined below) to expire or the failure to obtain
any necessary governmental or regulatory approvals, Acquisition shall extend
(and re-extend) the Offer through September 30, 1996.

         (b)  As soon as practicable on the date of commencement of the Offer,
Parent and Acquisition shall file with the Securities and Exchange Commission
(the "SEC") a Tender Offer Statement on Schedule 14D-1 with respect to the Offer
which will contain the offer to purchase and form of the related letter of
transmittal (together with any supplements or amendments thereto, the "Offer
Documents").  Parent, Acquisition and the Company each agrees promptly to
correct any information provided by it for use in the Offer Documents if and to
the extent that any such information shall have become false or misleading in
any material respect and Parent and Acquisition each further agrees to take all
steps necessary to cause the Offer Documents as so corrected to be filed with
the SEC and to be disseminated to holders of Shares, in each case as and to the
extent required by applicable federal securities laws.  The Company and its
counsel shall be given a reasonable opportunity to review and comment on the
Offer Documents prior to their filing with the SEC and shall be provided with
any comments Parent, Acquisition and their counsel may receive from the SEC or
its staff with respect to the Offer Documents promptly after receipt of such
comments.

    Section 1.2    COMPANY ACTION.  (a)  The Company hereby approves of and
consents to the Offer and represents and warrants that the Board, at a meeting
duly called and held on March 29, 1996, unanimously (i) determined that this
Agreement and the transactions contemplated hereby, including the Offer and the
Merger, are fair to and in the best interests of the stockholders of the
Company, (ii) approved this Agreement and the transactions contemplated hereby,
including the Offer and the Merger and (iii) resolved to recommend that the
stockholders of the Company accept the Offer, tender their Shares thereunder to
Acquisition and, if required by applicable law, approve and adopt this Agreement
and the Merger.  The Company further represents and warrants that Alex. Brown &
Sons Incorporated ("Alex. Brown") has delivered to the Board its written opinion
to the effect that, as of the date of such opinion, the consideration to be
received by the holders of Shares pursuant to the Offer and the Merger is fair
to such holders from a financial point of view.  The Company has been authorized
by Alex. Brown to permit the inclusion of such


                                         -3-

<PAGE>

fairness opinion in the Offer Documents and the Schedule 14D-9 referred to below
and the Proxy Statement referred to in Section 4.7.  Subject to the fiduciary
duties of the Board under applicable law (as determined in good faith after
consultation with independent counsel), the Company hereby consents to the
inclusion in the Offer Documents of the recommendations of the Board described
in this Section 1.2(a).

         (b)  As soon as practicable on the date of commencement of the Offer,
the Company shall file with the SEC a Solicitation/Recommendation Statement on
Schedule 14D-9 (together with any amendments or supplements thereto, the
"Schedule 14D-9") and shall mail the Schedule 14D-9 to the stockholders of the
Company promptly after the commencement of the Offer.  The Schedule 14D-9 shall,
subject to the fiduciary duties of the Board under applicable law (as determined
in good faith after consultation with independent counsel), at all times contain
the determinations, approvals and recommendations described in Section 1.2(a).
Parent, Acquisition and the Company each agrees promptly to correct any
information provided by it for use in the Schedule 14D-9 if and to the extent
that any such information shall have become false or misleading in any material
respect and the Company further agrees to take all steps necessary to cause the
Schedule 14D-9 as so corrected to be filed with the SEC and to be disseminated
to holders of Shares, in each case as and to the extent required by applicable
federal securities laws.  Parent, Acquisition and their counsel shall be given a
reasonable opportunity to review and comment on the Schedule 14D-9 prior to its
filing with the SEC and shall be provided with any comments the Company and its
counsel may receive from the SEC or its staff with respect to the Schedule 14D-9
promptly after receipt of such comments.

         (c)  In connection with the Offer, the Company will promptly furnish
Acquisition with mailing labels, security position listings and any available
listing or computer file containing the names and addresses of the record
holders of the Shares as of a recent date and shall furnish Acquisition with
such additional information and assistance (including, without limitation,
updated lists of stockholders, mailing labels and lists of securities positions)
as Acquisition or its agents may reasonably request in communicating the Offer
to the record and beneficial holders of Shares.  Subject to the requirements of
applicable law, and except for such steps as are necessary to disseminate the
Offer Documents and any other documents necessary to consummate the Merger,
Acquisition and its affiliates and associates shall hold in confidence the
information contained in any such labels, listings and files, will use such
information only in connection with the Offer and the Merger, and, if this
Agreement shall be terminated, will deliver to the Company all copies of such
information then in their possession.


                                         -4-

<PAGE>

    Section 1.3    BOARDS OF DIRECTORS AND COMMITTEES; SECTION 14(f).  (a)
Promptly upon the purchase by Acquisition of Shares pursuant to the Offer and
from time to time thereafter, Acquisition shall be entitled to designate up to
such number of directors, rounded up to the next whole number, on the Board that
equals the product of (i) the total number of directors on the Board (giving
effect to the election of any additional directors pursuant to this Section) and
(ii) the percentage that the number of Shares owned by Acquisition and its
affiliates (including any Shares purchased pursuant to the Offer) bears to the
total number of outstanding Shares, and the Company shall, upon request by
Acquisition, subject to the provisions of Section 1.3(b), promptly either
increase the size of the Board (and shall, if necessary, amend the Company's By-
Laws to permit such an increase) or use its reasonable best efforts to secure
the resignation of such number of directors as is necessary to enable
Acquisition's designees to be elected to the Board and shall cause Acquisition's
designees to be so elected.  Promptly upon request by Acquisition, the Company
will, subject to the provisions of Section 1.3(b), use its reasonable best
efforts to cause persons designated by Acquisition to constitute the same
percentage as the number of Acquisition's designees to the Board bears to the
total number of directors on the Board on (i) each committee of the Board, (ii)
each board of directors or similar governing body or bodies of each subsidiary
of the Company designated by Acquisition and (iii) each committee of each such
board or body.

         (b)  The Company's obligations to appoint designees to the Board shall
be subject to Section 14(f) of the Securities Exchange Act of 1934, as amended
(the "Exchange Act"), and Rule 14f-1 promulgated thereunder.  The Company shall
promptly take all actions required pursuant to Section 14(f) and Rule 14f-1 in
order to fulfill its obligations under this Section 1.3 and shall include in the
Schedule 14D-9 or a separate Rule 14f-1 Statement provided to shareholders such
information with respect to the Company and its officers and directors as is
required under Section 14(f) and Rule 14f-1.  Parent or Acquisition will supply
to the Company in writing and be solely responsible for any information with
respect to either of them and their nominees, officers, directors and affiliates
required by Section 14(f) and Rule 14f-1.

         (c)  Following the election or appointment of Acquisition's designees
pursuant to this Section 1.3 and prior to the Effective Time (as defined below),
any amendment of this Agreement or the Restated Articles of Organization or By-
Laws of the Company, any termination of this Agreement by the Company, any
extension by the Company of the time for the performance of any of the
obligations or other acts of Parent or Acquisition or any waiver of any of the
Company's rights hereunder will require


                                         -5-

<PAGE>

the concurrence of a majority of the directors of the Company then in office who
are not designees of Acquisition or employees of the Company.

                                      ARTICLE II

                                      THE MERGER

    Section 2.1    THE MERGER.  At the Effective Time (as defined below) and
upon the terms and subject to the conditions of this Agreement and Massachusetts
Law, Acquisition shall be merged with and into the Company whereupon the
separate corporate existence of Acquisition shall cease and the Company shall
continue as the surviving corporation (the "Surviving Corporation").  At
Acquisition's option, the Merger may be structured so that any direct or
indirect subsidiary of Parent is merged with and into the Company.  In the event
of such election, the parties agree to execute an appropriate amendment to this
Agreement in order to reflect such election.

    Section 2.2    EFFECTIVE TIME; CLOSING.  As soon as practicable after the
satisfaction or waiver of the conditions set forth in Article VII, the parties
hereto will file articles of merger with the Secretary of the Commonwealth of
Massachusetts and make all other filings or recordings required by Massachusetts
Law in connection with the Merger.  The Merger shall become effective at such
time as the articles of merger are duly filed with the Secretary of the
Commonwealth of Massachusetts, or at such later time as is specified in the
articles of merger (the "Effective Time").  Prior to such filing, a closing
shall be held at the offices of Mayer, Brown & Platt, 190 South LaSalle Street,
Chicago, Illinois  60603, or such other place as the parties shall agree, for
the purpose of confirming the satisfaction or waiver of the conditions set forth
in Article VII.

    Section 2.3    EFFECTS OF THE MERGER; SUBSEQUENT ACTIONS.  (a)  The Merger
shall have the effects set forth in Massachusetts Law.  Without limiting the
generality of the foregoing, and subject thereto, at the Effective Time, all the
properties, rights, privileges, powers and franchises of the Company and
Acquisition shall vest in the Surviving Corporation, and all debts, liabilities
and duties of the Company and Acquisition shall become the debts, liabilities
and duties of the Surviving Corporation.

         (b)  If, at any time after the Effective Time, the Surviving
Corporation shall consider or be advised that any deeds, bills of sale,
assignments, assurances or any other actions or things are necessary or
desirable to vest, perfect or confirm of record or otherwise in the Surviving
Corporation its


                                         -6-

<PAGE>

right, title or interest in, to or under any of the rights, properties or assets
of the Company or Acquisition acquired or to be acquired by the Surviving
Corporation as a result of or in connection with the Merger, or otherwise to
carry out this Agreement, the officers and directors of the Surviving
Corporation shall be authorized to execute and deliver, in the name and on
behalf of the Company or Acquisition, all such deeds, bills of sale, assignments
and assurances and to take and do, in the name and on behalf of each of such
corporations or otherwise, all such other actions and things as may be necessary
or desirable to vest, perfect or confirm of record or otherwise any and all
right, title and interest in, to and under such rights, properties or assets of
the Surviving Corporation or otherwise to carry out this Agreement.

    Section 2.4    ARTICLES OF ORGANIZATION; BY-LAWS.  (a)  Subject to Section
6.5, at the Effective Time, the Articles of Organization of Acquisition in
effect immediately prior to the Effective Time shall be the Articles of
Organization of the Surviving Corporation until amended in accordance with
applicable law; PROVIDED, however, that at the Effective Time, Article I of the
Articles of Organization of the Surviving Corporation shall be amended to read
as follows:  "The name by which the corporation shall be known is MediSense,
Inc."

         (b)  The By-Laws of Acquisition in effect at the Effective Time shall
be the By-Laws of the Surviving Corporation until amended in accordance with
applicable law.

         (c)  The Articles of Organization of the Surviving Corporation shall
state that the purpose of the Surviving Corporation shall be to carry on any
manufacturing, mercantile, selling, management, service or other business,
operation or activity which may be lawfully carried on by a corporation
organized under Massachusetts Law.  The Surviving Corporation initially shall be
authorized to issue up to 1,000 shares of its common stock, par value $0.01 per
share.

    Section 2.5    DIRECTORS.  The directors of Acquisition at the Effective
Time shall be the initial directors of the Surviving Corporation, each to hold
office in accordance with the Articles of Organization and By-Laws of the
Surviving Corporation and until his or her successor is duly elected and
qualified.

    Section 2.6    OFFICERS.  The officers of the Company at the Effective
Time, and any additional individuals designated by Parent, shall be the initial
officers of the Surviving Corporation, each to hold office in accordance with
the Articles of Organization and By-Laws of the Surviving Corporation and until
his or her successor is duly appointed and qualified.


                                         -7-

<PAGE>

    Section 2.7    CONVERSION OF SECURITIES.  At the Effective Time, by virtue
of the Merger and without any action on the part of Parent, Acquisition, the
Company or the holder of any of the following securities:

         (a)  Each Share issued and outstanding immediately prior to the
Effective Time (other than Shares to be cancelled pursuant to Section 2.7(b)
hereof and Dissenting Shares (as defined in Section 3.1)), shall by virtue of
the Merger and without any action on the part of the holder thereof be cancelled
and extinguished and be converted into the right to receive an amount equal to
the Per Share Amount (the "Merger Consideration").

         (b)  Each Share issued and outstanding immediately prior to the
Effective Time and owned by Parent or Acquisition or any direct or indirect
subsidiary of Parent or Acquisition, or which is held in the treasury of the
Company or any of its subsidiaries, shall be cancelled and retired and no
payment of any consideration shall be made with respect thereto.

         (c)  Each share of common stock, par value $0.01 per share, of
Acquisition issued and outstanding immediately prior to the Effective Time shall
be converted into and become one validly issued, fully paid and nonassessable
share of common stock, par value $0.01 per share, of the Surviving Corporation.

    Section 2.8    STOCK OPTIONS.  Immediately prior to the Effective Time,
each outstanding option (including any related stock appreciation right) (an
"Option") issued pursuant to the Company's 1983 Stock Option Plan, 1992
Directors' Stock Option Plan, 1993 Stock Option Plan, 1995 U.K. Stock Option
Scheme and 1995 Directors' Stock Option Plan or any other option plan or
agreement of the Company or other outstanding options to purchase Common Stock
granted by the Company to its executive officers, whether or not then
exercisable, shall be cancelled by the Company, and each holder of a cancelled
Option shall be entitled to receive at the Effective Time or as soon as
practicable thereafter from the Company in consideration for the cancellation of
such Option an amount in cash (less applicable withholding taxes) equal to the
product of (i) the number of shares of Common Stock previously subject to such
Option and (ii) the excess, if any, of the Merger Consideration over the
exercise price per share of Common Stock previously subject to such Option.

    Section 2.9    COMPANY EMPLOYEE STOCK PURCHASE PLAN.  The Company shall
take such actions as are necessary to cause the exercise date applicable to the
then current Purchase Period (as defined in the Company's 1994 Employee Stock
Purchase Plan (the "Stock Purchase Plan")) to be the last trading day on which
the Common Stock is traded on the Nasdaq National Market immediately


                                         -8-

<PAGE>

prior to the Effective Time (the "Final Company Purchase Date"); PROVIDED that
such change in the exercise date shall be conditioned upon the consummation of
the Merger.  On the Final Company Purchase Date, the Company shall apply the
funds credited as of such date under the Company Stock Purchase Plan within each
participant's payroll withholdings account to the purchase of whole shares of
Common Stock in accordance with the terms of the Company Stock Purchase Plan.
The cost to each participant in the Company Stock Purchase Plan for shares of
the Common Stock shall be the lower of 85% of the closing sale price of the
Common Stock, as reported by Nasdaq National Market (as published in THE WALL
STREET JOURNAL) on (i) the first day of the then current Purchase Period or (ii)
the last trading day on or prior to the Final Company Purchase Date.

    Section 2.10   STOCKHOLDERS' MEETING.  If approval by the Company's
stockholders is required by applicable law to consummate the Merger, the
Company, acting through the Board, shall in accordance with applicable law and
subject to the fiduciary duties of the Board under applicable law (as determined
in good faith after consultation with independent counsel), as soon as
practicable following the consummation of the Offer:

              (i)   duly call, give notice of, convene and hold an annual
    or special meeting of its stockholders (the "Stockholders' Meeting")
    for the purpose of considering and taking action upon this Agreement;

              (ii)  include in the Proxy Statement (as defined in Section
    4.7) the recommendation of the Board that stockholders of the Company
    vote in favor of the approval and adoption of this Agreement and the
    transactions contemplated hereby; and

              (iii)  use its reasonable best efforts (A) to obtain and
    furnish the information required to be included by it in the Proxy
    Statement and, after consultation with Parent, respond promptly to any
    comments made by the SEC with respect to the Proxy Statement and any
    preliminary version thereof and cause the Proxy Statement to be mailed
    to its stockholders at the earliest practicable time following the
    consummation of the Offer and (B) to obtain the necessary approvals by
    its stockholders of this Agreement and the transactions contemplated
    hereby.

    At such meeting, Parent and Acquisition will vote all Shares owned by them
in favor of this Agreement and the transactions contemplated hereby.


                                         -9-

<PAGE>

                                     ARTICLE III

                        DISSENTING SHARES; EXCHANGE OF SHARES

    Section 3.1    DISSENTING SHARES.  Notwithstanding anything in this
Agreement to the contrary, Shares outstanding immediately prior to the Effective
Time and held by a holder who has not voted in favor of the Merger or consented
thereto in writing and who has demanded appraisal for such Shares in accordance
with Massachusetts Law ("Dissenting Shares") shall not be converted into a right
to receive the Merger Consideration unless such holder fails to perfect or
withdraws or otherwise loses his, her or its right to appraisal.  If, after the
Effective Time, such holder fails to perfect or withdraws or loses his, her or
its right to appraisal, such Shares shall be treated as if they had been
converted as of the Effective Time into a right to receive the Merger
Consideration without interest thereon.  The Company shall give Parent prompt
notice of any demands received by the Company for appraisal of Shares, and,
prior to the Effective Time, Parent shall have the right to participate in all
negotiations and proceedings with respect to such demands.  Prior to the
Effective Time, the Company shall not, except with the prior written consent of
Parent, make any payment with respect to, or settle or offer to settle, any such
demands.

    Section 3.2    EXCHANGE OF CERTIFICATES.  (a)  Prior to the Effective Time,
a bank or trust company shall be designated by Parent (the "Paying Agent") to
act as agent in connection with the Merger to receive the funds to which holders
of Shares shall become entitled pursuant to Section 2.7(a).  Promptly after the
Effective Time, the Surviving Corporation shall cause to be mailed to each
record holder, as of the Effective Time, of a certificate or certificates (the
"Certificates") that, prior to the Effective Time, represented Shares and a form
of letter of transmittal and instructions for use in effecting the surrender of
the Certificates for payment of the Merger Consideration therefor.  Upon the
surrender of each such Certificate formerly representing Shares, together with
such letter of transmittal, duly completed and validly executed in accordance
with the instructions thereto, the Paying Agent shall pay the holder of such
Certificate the Merger Consideration multiplied by the number of Shares formerly
represented by such Certificate, in exchange therefor, and such Certificate
shall forthwith be cancelled.  Until so surrendered and exchanged, each such
Certificate (other than Certificates representing Dissenting Shares or Shares
held by Parent, Acquisition or the Company, or any direct or indirect subsidiary
thereof) shall represent solely the right to receive the Merger Consideration.
No interest shall be paid or accrue on the Merger Consideration.  If the Merger
Consideration (or any portion thereof) is to be delivered to any person other
than the person in whose name the Certificate


                                         -10-

<PAGE>

formerly representing Shares surrendered in exchange therefor is registered, it
shall be a condition to such exchange that the Certificate so surrendered shall
be properly endorsed or otherwise be in proper form for transfer and that the
person requesting such exchange shall pay to the Paying Agent any transfer or
other taxes required by reason of the payment of the Merger Consideration to a
person other than the registered holder of the Certificate surrendered, or shall
establish to the satisfaction of the Paying Agent that such tax has been paid or
is not applicable.

         (b)  When and as needed, Parent or Acquisition shall deposit, or cause
to be deposited, in trust with the Paying Agent the Merger Consideration to
which holders of Shares shall be entitled at the Effective Time pursuant to
Section 2.7(a) hereof.

         (c)  The Merger Consideration shall be invested by the Paying Agent,
as directed by Parent, provided such investments shall be limited to direct
obligations of the United States of America, obligations for which the full
faith and credit of the United States of America is pledged to provide for the
payment of principal and interest, commercial paper rated of the highest quality
by Moody's Investors Service, Inc. or Standard & Poor's Corporation, or
certificates of deposit issued by a commercial bank having at least
$1,000,000,000 in assets.

         (d)  Promptly following the date which is six months after the
Effective Time, Parent will cause the Paying Agent to deliver to the Surviving
Corporation all cash and documents in its possession relating to the
transactions described in this Agreement, and the Paying Agent's duties shall
terminate.  Thereafter, each holder of a Certificate formerly representing a
Share may surrender such Certificate to the Surviving Corporation and (subject
to applicable abandoned property, escheat and similar laws) receive in exchange
therefor the Merger Consideration, without any interest thereon.

         (e)  After the Effective Time, there shall be no transfers on the
stock transfer books of the Surviving Corporation of any Shares.  If, after the
Effective Time, Certificates formerly representing Shares are presented to the
Surviving Corporation or the Paying Agent, they shall be cancelled and exchanged
for the Merger Consideration, as provided in this Article III, subject to
applicable law in the case of Dissenting Shares.

                                      ARTICLE IV

                    REPRESENTATIONS AND WARRANTIES OF THE COMPANY


                                         -11-


<PAGE>

    Except as set forth in the schedules delivered by the Company to Parent and
Acquisition concurrently with the execution of this Agreement and the SEC
Reports (as defined in Section 4.5) filed prior to the date hereof, the Company
represents and warrants to Parent and Acquisition as follows:

    Section 4.1    ORGANIZATION AND QUALIFICATION; SUBSIDIARIES.  (a)  Each of
the Company and its subsidiaries is a corporation duly organized, validly
existing and in good standing under the laws of the jurisdiction of its
incorporation and has all requisite corporate power and authority to own, lease
and operate its properties and to carry on its business as now being conducted,
except where the failure to be so organized, existing and in good standing or to
have such power and authority would not, individually or in the aggregate, have
a material adverse effect on the business, assets, liabilities, results of
operations, reserves or financial condition of the Company and its subsidiaries,
taken as a whole (a "Material Adverse Effect"); PROVIDED, HOWEVER, that the term
Material Adverse Effect shall not include a material adverse change which
affects the glucose monitoring industry as a whole.

         (b)  Each of the Company and its subsidiaries is duly qualified or
licensed and in good standing to do business in each jurisdiction (including any
foreign country) in which the property owned, leased or operated by it or the
nature of the business conducted by it makes such qualification or licensing
necessary, except where the failure to be so duly qualified or licensed and in
good standing would not, individually or in the aggregate, have a Material
Adverse Effect.

         (c)  The Company has heretofore made available to Parent complete and
correct copies of the Company's Restated Articles of Organization and By-Laws
and the equivalent organizational documents of each of its subsidiaries, each as
amended to the date hereof.  Such Restated Articles of Organization, By-Laws and
equivalent organizational documents are in full force and effect and no other
organizational documents are applicable to or binding upon the Company or its
subsidiaries.  The Company is not in violation of any of the provisions of its
Restated Articles of Organization or By-Laws and no subsidiary of the Company is
in violation of any of the provisions of such subsidiary's equivalent
organizational documents except, in each case, for such violations that would
not, individually or in the aggregate, have a Material Adverse Effect.

         (d)  The Company has heretofore furnished to Parent a complete and
correct list of all entities in which the Company owns, directly or indirectly,
any equity or voting interest, which list sets forth the amount of capital stock
of or other


                                         -12-

<PAGE>

equity interests in such entities, directly or indirectly.  No entity in which
the Company owns, directly or indirectly, less than a 50% equity interest is,
individually or when taken together with all other such entities, material to
the business of the Company and its subsidiaries, taken as a whole.  Neither the
Company, nor any of its subsidiaries, is subject to any outstanding material
obligation or has made any commitment to purchase any additional equity
interests, make any capital contributions to or invest any funds in any business
or entity other than any wholly-owned subsidiary of the Company.

    Section 4.2    CAPITALIZATION OF THE COMPANY AND ITS SUBSIDIARIES.  The
authorized capital stock of the Company consists of (i) 30,000,000 shares of
Common Stock of which, as of March 28, 1996, 16,792,849 shares of Common Stock
were issued and outstanding (including 8,173 shares subject to restrictions
issued pursuant to employee benefit plans of the Company and its subsidiaries or
otherwise), (ii) 3,000,000 shares of class A common stock, par value $0.01 per
share, of which, as of March 28, 1996, no shares were issued and outstanding,
(iii) 1,500,000 shares of Class B Common Stock, of which, as of March 28, 1996,
897,340 shares were issued and outstanding and (iv) 1,000,000 shares of
undesignated preferred stock, of which, as of March 28, 1996, no shares were
issued and outstanding.  All outstanding shares of capital stock of the Company
have been validly issued, and are fully paid, nonassessable and free of
preemptive rights.  As of March 28, 1996, Options to purchase an aggregate of
2,500,913 shares of Common Stock were outstanding and the weighted average
exercise price of such Options was $12.8656 per share of Common Stock.  Except
as set forth above, and except as a result of the exercise of Options
outstanding as of March 28, 1996, there are outstanding (i) no shares of capital
stock or other voting securities of the Company, (ii) no securities of the
Company convertible into or exchangeable for shares of capital stock or voting
securities of the Company, (iii) no options, subscriptions, warrants,
convertible securities, calls or other rights to acquire from the Company, and
no obligation of the Company to issue, deliver or sell any capital stock, voting
securities or securities convertible into or exchangeable for capital stock or
voting securities of the Company and (iv) no equity equivalents, interests in
the ownership or earnings of the Company or other similar rights (collectively,
"Company Securities").  There are no outstanding obligations of the Company or
any of its subsidiaries to repurchase, redeem or otherwise acquire any Company
Securities, other than the Company's obligations hereunder to cancel the
Options.  Each of the outstanding shares of capital stock of each of the
Company's subsidiaries is duly authorized, validly issued, fully paid and
nonassessable and is directly or indirectly owned by the Company, free and clear
of all security interests, liens, claims, pledges, charges, voting agreements or
other encumbrances of any nature


                                         -13-

<PAGE>

whatsoever (collectively, "Liens").  There are no existing options, calls or
commitments of any character relating to the issued or unissued capital stock or
other securities of any subsidiary of the Company.

    Section 4.3    AUTHORITY RELATIVE TO THIS AGREEMENT.  The Company has all
necessary corporate power and authority to execute and deliver this Agreement,
to perform its obligations hereunder and to consummate the transactions
contemplated hereby.  The execution, delivery and performance of this Agreement
and the consummation of the transactions contemplated hereby have been duly and
validly authorized by the Board and no other corporate proceedings on the part
of the Company are necessary to authorize this Agreement or to consummate the
transactions so contemplated (other than, with respect to the Merger, the
approval and adoption of this Agreement by the holders of a majority of the
outstanding Shares if and to the extent required by applicable law and the
filing of the appropriate merger documents as required by Massachusetts Law).
This Agreement has been duly and validly executed and delivered by the Company
and constitutes a legal, valid and binding agreement of the Company enforceable
against the Company in accordance with its terms.

    Section 4.4    NON-CONTRAVENTION; REQUIRED FILINGS AND CONSENTS. (a)  The
execution, delivery and performance by the Company of this Agreement and the
consummation of the transactions contemplated hereby (including the Merger) do
not and will not (i) contravene or conflict with the Restated Articles of
Organization or By-Laws of the Company or the equivalent organizational
documents of any of its subsidiaries; (ii) assuming that all consents,
authorizations and approvals contemplated by subsection (b) below have been
obtained and all filings described therein have been made, contravene or
conflict with or constitute a violation of any provision of any law, regulation,
judgment, injunction, order or decree binding upon or applicable to the Company,
any of its subsidiaries or any of their respective properties; (iii) conflict
with, or result in the breach or termination of any provision of or constitute a
default (with or without the giving of notice or the lapse of time or both)
under, or give rise to any right of termination, cancellation, or loss or
impairment of any benefit to which the Company or any of its subsidiaries is
entitled under any provision of any agreement, contract, license or other
instrument binding upon the Company, any of its subsidiaries or any of their
respective properties, or allow the acceleration of the performance of, any
obligation of the Company or any of its subsidiaries under any indenture,
mortgage, deed of trust, lease, license, contract, instrument or other agreement
to which the Company or any of its subsidiaries is a party or by which the
Company or any of its subsidiaries or any of their respective assets or
properties is subject or bound; or (iv) result in the


                                         -14-

<PAGE>

creation or imposition of any Lien on any asset of the Company or any of its
subsidiaries, except in the case of clauses (ii), (iii) and (iv) for any such
contraventions, conflicts, violations, breaches, terminations, defaults,
cancellations, losses, accelerations and Liens which would not individually or
in the aggregate have a Material Adverse Effect or materially interfere with the
consummation of the transactions contemplated by this Agreement.

         (b)  The execution, delivery and performance by the Company of this
Agreement and the consummation of the transactions contemplated hereby
(including the Merger) by the Company require no action by or in respect of, or
filing with, any governmental body, agency, official or authority (either
domestic, foreign or supranational) other than (i) the filing of articles of
merger in accordance with Massachusetts Law; (ii) compliance with any applicable
requirements of the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as
amended (the "HSR Act"); (iii) compliance of any applicable requirements of any
laws or regulations relating to the regulation of monopolies or competition in
Germany; (iv) compliance with any applicable requirements of the Exchange Act
and state securities, takeover and Blue Sky laws; and (v) such actions or
filings which, if not taken or made, would not, individually or in the
aggregate, have a Material Adverse Effect or materially interfere with the
consummation of the transactions contemplated by this Agreement.

    Section 4.5    SEC REPORTS.   (a)  The Company has filed all required
forms, reports and documents with the SEC since July 8, 1994 (collectively, the
"SEC Reports"), each of which has complied in all material respects with
applicable requirements of the Securities Act of 1933, as amended (the
"Securities Act"), and the Exchange Act.  As of their respective dates, none of
the SEC Reports, including, without limitation, any financial statements or
schedules included therein, contained any untrue statement of a material fact or
omitted to state a material fact required to be stated therein or necessary in
order to make the statements therein, in light of the circumstances under which
they were made, not misleading.  The audited consolidated financial statements
and unaudited consolidated interim financial statements of the Company included
in the SEC Reports fairly present, in all material respects and in conformity
with generally accepted accounting principles applied on a consistent basis
(except as may be indicated in the notes thereto), the consolidated financial
position of the Company and its consolidated subsidiaries as of the dates
thereof and their consolidated results of operations and cash flows for the
periods then ended (subject to normal year-end adjustments in the case of any
unaudited interim financial statements).


                                         -15-

<PAGE>

         (b)  Except as reflected or reserved against in the audited
consolidated balance sheet of the Company and its subsidiaries at December 31,
1995, the Company and its subsidiaries have no liabilities of any nature
(whether accrued, absolute, contingent or otherwise), except for liabilities
incurred in the ordinary course of business since December 31, 1995 or
liabilities which would not, individually or in the aggregate, have a Material
Adverse Effect.  Neither the Company nor any of its subsidiaries is liable as an
indemnitor, guarantor, surety or endorser, and no person has the power to
confess judgment against the Company or any of its subsidiaries, assets,
properties or business except as would not, individually or in the aggregate,
result in or reasonably be likely to result in a Material Adverse Effect.

    Section 4.6    ABSENCE OF CERTAIN CHANGES; DERIVATIVES.     (a)  Since
December 31, 1995, except as specifically disclosed in the SEC Reports filed
prior to the date of this Agreement, neither the Company nor any of its
subsidiaries has (A) except as disclosed on Schedule 4.6, taken any of the
actions set forth in Sections 6.1(a), (c), (d), (g), (h)(i), (h)(ii), (h)(iii),
(i), (j) or (k), (B) taken any of the actions set forth in Sections 6.1(e) or
(f) except, in each case, as would not individually or in the aggregate, result
in a Material Adverse Effect, or (C) entered into any transaction, or conducted
its business or operations, other than in the ordinary course of business
consistent with past practice.  Since December 31, 1995, there has not been any
change or event resulting in a Material Adverse Effect.

         (b)  As of the date hereof, there are no futures, forward, swap,
option or swaption contract, or any other financial instruments with similar
characteristics and/or generally characterized as a "derivative" security except
as would not, individually or in the aggregate, result in or reasonably be
likely to result in a Material Adverse Effect.

    Section 4.7    SCHEDULE 14D-9; OFFER DOCUMENTS; PROXY STATEMENT.  Neither
the Schedule 14D-9, nor any of the information provided by the Company and/or by
its auditors, legal counsel, financial advisors or other consultants or advisors
specifically for use in the Offer Documents shall, on the respective dates the
Schedule 14D-9, the Offer Documents or any supplements or amendments thereto are
filed with the SEC or on the date first published, sent or given to the
Company's stockholders, as the case may be, contain any untrue statement of a
material fact or omit to state any material fact required to be stated therein
or necessary in order to make the statements therein, in light of the
circumstances under which they were made, not misleading.  The proxy or
information statement or similar materials distributed to the Company's
stockholders in


                                         -16-

<PAGE>

connection with the Merger, including any amendments or supplements thereto (the
"Proxy Statement"), shall not, at the time filed with the SEC, at the time
mailed to the Company's stockholders, at the time of the Stockholders' Meeting
or at the Effective Time, contain any untrue statement of a material fact or
omit to state any material fact required to be stated therein or necessary in
order to make the statements therein, in light of the circumstances under which
they are made, not misleading.  Notwithstanding the foregoing, the Company makes
no representation or warranty with respect to any information provided by
Parent, Acquisition and/or by their auditors, legal counsel, financial advisors
or other consultants or advisors specifically for use in the Schedule 14D-9 or
the Proxy Statement.  The Schedule 14D-9 and the Proxy Statement will comply as
to form in all material respects with the provisions of the Exchange Act and the
rules and regulations thereunder.

    Section 4.8    FINDER'S FEE.  No broker, finder, investment banker or other
intermediary (other than Alex. Brown) is entitled to any brokerage, finder's or
other fee or commission in connection with the transactions contemplated by this
Agreement based upon arrangements made by and on behalf of the Company.  The
Company has heretofore furnished to Parent a complete and correct copy of all
agreements between the Company and Alex. Brown pursuant to which Alex. Brown
would be entitled to any payment relating to the transactions contemplated
hereby.

    Section 4.9    ABSENCE OF LITIGATION.   Except as disclosed on Schedule
4.9, there is no action, suit, claim, investigation or proceeding pending
against or, to the knowledge of the Company, threatened against, the Company or
any of its subsidiaries or any of their respective properties before any court
or arbitrator or any administrative, regulatory or governmental body, or any
agency or official (i) which, individually or in the aggregate, would reasonably
be likely to have a Material Adverse Effect; (ii) which, as of the date of this
Agreement, in any manner challenges or seeks to prevent, enjoin, alter or delay
the Offer or the Merger or any of the other transactions contemplated hereby; or
(iii) which, as of the date of this Agreement, alleges criminal action or
inaction and which, as of the Effective Time, alleges any criminal action or
inaction which would reasonably be likely to have a Material Adverse Effect.  As
of the date hereof, neither the Company nor any of its subsidiaries nor any of
their respective properties is subject to any order, writ, judgment, injunction,
decree, determination or award having, or which would reasonably  be expected to
have, a Material Adverse Effect or which would prevent or delay the consummation
of the transactions contemplated hereby.


                                         -17-

<PAGE>

    Section 4.10   TAXES.  (a) All federal, state, local, foreign and other Tax
returns, reports, information returns and statements of the Company and each of
its subsidiaries (including any consolidated Tax returns that include the income
or loss of the Company or any of its subsidiaries) required by law to be filed
or sent as of the Effective Time have been or will be duly filed or sent, except
where the failure to file or send such returns, reports or statements would not
have a Material Adverse Effect and to the best knowledge of the Company such
returns, reports and statements are or will be true, complete and correct in all
respects, except where the failure to be true, complete and correct would not
have a Material Adverse Effect.  All federal, state, local, foreign and other
taxes, assessments, fees and other governmental charges, including without
limitation income, gross receipts, net proceeds, alternative or add-on minimum,
ad valorem, value added, turnover, sales, use, property, personal property
(tangible and intangible), stamp, leasing, lease, user, excise, duty, franchise,
transfer, license, withholding, payroll, employment, fuel, excess profits,
occupational and interest equalization, windfall profits, severance, and other
charges (including interest and penalties) (collectively, "Taxes") imposed upon
the Company or any of its subsidiaries or any of the properties, assets or
income of the Company or any of its subsidiaries which are due and payable
through the Effective Time or claimed by any taxing authority to be due and
payable through the Effective Time have been or will be paid or reserved for, or
adequate provision will be made therefor, as of the Effective Time, other than
Taxes being contested in good faith by the Company or any of its subsidiaries
and other than where the failure to pay, reserve or provide for such Taxes would
not have a Material Adverse Effect.  The most recent financial statements
contained in the SEC Reports reflect an adequate tax reserve in accordance with
Generally accepted accounting principles.

    (b)  Neither the IRS nor any other taxing authority or agency, domestic or
foreign, has asserted or, to the best knowledge of the Company has threatened to
assert, against the Company or its subsidiaries any deficiency or claim for
additional Taxes which, if such deficiency or claims were finally resolved
against the Company or its subsidiaries, would have a Material Adverse Effect.

    (c)  The Company and all of its subsidiaries have paid or are withholding
and will pay when due to the proper taxing authorities all withholding amounts
required to be withheld with respect to all Taxes, including without limitation
sales and use Taxes and Taxes on income or benefits and taxes for unemployment,
social security or other similar programs with respect to salary and other
compensation of directors, officers and employees of the Company and its
subsidiaries, except where the failure to


                                         -18-



<PAGE>

withhold and pay such Taxes would not have a Material Adverse Effect.

    (d)  Neither the Company nor any of its subsidiaries has any liability for
any federal, state, local, foreign or other Taxes of any corporation or entity
other than the Company and its subsidiaries, including without limitation any
liability arising from the application of U.S. Treasury Regulations Section
1.1502-6 or any analogous provision of state, local or foreign law, except any
liability that would not have a Material Adverse Effect.

    (e)  Neither the Company nor any of its subsidiaries is or has been a party
to any Tax sharing agreement with any corporation other than the Company and its
subsidiaries, except any Tax sharing agreement under which the liability of the
Company or its subsidiaries would not have a Material Adverse Effect.

    (f)  To the best of the Company's knowledge and as of the date hereof, no
person who holds 5 percent or more of the stock of the Company is a "foreign
person" as defined in Section 1445(f)(3) of the Code.

    Section 4.11   EMPLOYEE BENEFITS.  (a) Schedule 4.11 lists all employee
pension plans (as defined in Section 3(2) of the Employee Retirement Income
Security Act of 1974, as amended ("ERISA")), all material employee welfare plans
(as defined in Section 3(1) of ERISA), and all other material bonus, stock
option, stock purchase, incentive, deferred compensation, supplemental
retirement, severance or termination and other similar fringe or employee
benefit plans, programs or arrangements, and any material current or former
employment, executive compensation or severance contracts or agreements, written
or otherwise, for the benefit of, or relating to, any employee of the Company,
any trade or business (whether or not incorporated) which is a member of a
controlled group including the Company or which is under common control with the
Company (an "ERISA Affiliate") within the meaning of Section 414 of the Code, or
Section 4001 of ERISA or any subsidiary of the Company, as well as each plan
with respect to which the Company or an ERISA Affiliate could incur liability
under Section 4069 (if such plan has been or were terminated) or Section 4212(c)
of ERISA (together, all of the foregoing plans, programs, arrangements contracts
or agreements referred to as the "Employee Plans").  There have been made
available to Parent copies of (i) each such written Employee Plan (other than
those referred to in Section 4(b)(4) of ERISA), and (ii) the most recent summary
plan description and annual report on Form 5500 series, with accompanying
schedules and attachments, filed with respect to each Employee Plan required to
make such a filing.  Except as provided at Section 4.11(c), for purposes of this
Section 4.11,


                                         -19-

<PAGE>

the term "material," used with respect to any Employee Plan, shall mean that the
Company or an ERISA Affiliate has incurred or may incur obligations, or has or
may have liabilities, in an amount exceeding $400,000 with respect to, or may
have or under, such Employee Plan.

    (b) (i) None of the Employee Plans promises or provides retiree medical or
other retiree welfare benefits to any person, and none of the Employee Plans is
a "multiemployer plan" as such term is defined in Section 3(37) of ERISA: (ii)
there has been no "prohibited transaction," as such term is defined in Section
406 of ERISA and Section 4975 of the Code, with respect to any Employee Plan,
which could result in any material liability of the Company or any of its
subsidiaries; (iii) all Employee Plans are in compliance in all material
respects with the requirements prescribed by any and all statutes (including
ERISA and the Code), orders or governmental rules and regulations currently in
effect with respect thereto (including all applicable requirements for
notification to participants or the Department of Labor, Internal Revenue
Service (the "IRS") or Secretary of the Treasury) and the Company and each of
its subsidiaries have performed all material obligations required to be
performed by them under, are not in any material respect in default under or
violation of, and have no knowledge of any default or violation by any other
party to, any of the Employee Plans, (iv) each Employee Plan intended to qualify
under Section 401(a) of the Code and each trust intended to qualify under
Section 501(a) of the Code is the subject of a favorable determination letter
from the IRS and, to the Company's knowledge, nothing has occurred which may
reasonably be expected to impair such determination, (v) all contributions
required to be made to any Employee Plan pursuant to Section 412 of the Code, or
the terms of the Employee Plan, have been made on or before their due dates;
(vi) none of the Employee Plans are subject to Title IV of ERISA and none is
intended to be a VEBA under Section 501(c)(9).

         (c)  No amounts payable under any Employee Plan or pursuant to this
Agreement (including but not limited to payments pursuant to Section 2.8 hereof)
will fail to be deductible for federal income tax purposes by virtue of Section
280G of the Code.  For purposes of this Section 4.11 the term "Employee Plan"
shall include all Employee Plans described at Section 4.11(a), as well as any
plan, program, arrangement, contract or agreement that would be an Employee Plan
described at Section 4.11(a), but for the requirement that such plan, program,
arrangement, contract or agreement be "material."

         (d)  The consummation of the transactions contemplated by this
Agreement will not under any Employee Plans (i) entitle any current or former
employee or officer of the Company or any ERISA Affiliate to severance pay,
unemployment compensation or


                                         -20-

<PAGE>

any other payment, (except as expressly provided in this Agreement or (ii)
accelerate the time of payment or vesting (except in the case of stock options),
or increase the amount of compensation due any such employee or officer.

         (e)  There are no material pending, threatened or anticipated claims
by or on behalf of any Employee Plan, by any employee or beneficiary covered
under any such Employee Plan, or otherwise involving any such Plan (other than
routine claims for benefits).

         (f)  The Company has the right to terminate any Plan which is a
welfare benefit plan, as that term is defined in section 3(1) of ERISA.

    Section 4.12   COMPLIANCE.  Neither the Company nor any of its subsidiaries
is in violation of, or has violated, any applicable provisions of (i) any laws,
rules, statutes, orders, ordinances or regulations or (ii) any note, bond,
mortgage, indenture, contract, agreement, lease, license, permit, franchise, or
other instrument or obligation to which the Company or its subsidiaries is a
party or by which the Company or any of its subsidiaries or its or any of their
respective properties are bound or affected, which, in the case of either
subsection (i) or (ii), individually or in the aggregate, would result or
reasonably be likely to result in a Material Adverse Effect.  Without limiting
the generality of the foregoing, neither the Company nor any of its subsidiaries
is in violation of, or has violated any applicable provisions of the Foreign
Corrupt Practices Act, the Trading with the Enemy Act, the Anti-Economic
Discrimination Act or any law or regulation relating to Medicare or Medicaid
anti-kickback fraud and abuse, except for such violations that would not,
individually or in the aggregate, result in or reasonably be likely to result in
a Material Adverse Effect.

    Section 4.13   ENVIRONMENTAL MATTERS.  (a)  The Company and its
subsidiaries are in compliance with all applicable Environmental Laws (as
defined below) (which compliance includes, but is not limited to, the possession
by the Company and its subsidiaries of all permits and other governmental
authorizations required under applicable Environmental Laws, and compliance with
the terms and conditions thereof), except for any noncompliance that
individually or in the aggregate would not reasonably be expected to have a
Material Adverse Effect.  To the knowledge of Cheryl Lawton or Robert Coleman,
neither the Company nor any of its subsidiaries has received any communication
(written or oral), whether from a governmental authority, citizens group,
employee or otherwise, that alleges that the Company or any of its subsidiaries
is not in such compliance, and there are no past or present (or to the knowledge
of the Company, future) actions,


                                         -21-

<PAGE>

activities, circumstances, conditions, events or incidents that may prevent or
interfere with such compliance in the future, except for any such interference
that would not reasonably be likely to have a Material Adverse Effect.

         (b)  There is no Environmental Claim (as defined below) pending or, to
the knowledge of the Company, threatened against the Company or any of its
subsidiaries, or, to the knowledge of the Company, against any person or entity
whose liability for any Environmental Claim the Company or any of its
subsidiaries has or may have retained or assumed either contractually or by
operation of law, which, individually or in the aggregate, would reasonably be
likely to have a Material Adverse Effect.

         (c)  There are no past or present (or to the knowledge of the Company,
future) actions, activities, circumstances, conditions, events or incidents
(including, without limitation, the release, emission, discharge, presence or
disposal of any Hazardous Material (as defined below)) which could reasonably be
likely to form the basis of any Environmental Claim against the Company or any
of its subsidiaries, or, to the knowledge of the Company, against any person or
entity whose liability for any Environmental Claim the Company or any of its
subsidiaries has or may have retained or assumed either contractually or by
operation of law, which, in either case, individually or in the aggregate, would
reasonably be likely to have a Material Adverse Effect.

         (d)  To the knowledge of Cheryl Lawton and Robert Coleman, neither the
Company nor any of its subsidiaries has received any request for information
regarding the contamination, or notice that it is a potentially responsible
party for the Cleanup (as defined below), of any property, whether or not owned
or operated by the Company or any of its subsidiaries, which individually or in
the aggregate would reasonably be likely to have a Material Adverse Effect.

         (e)  No transfers of permits or other governmental authorizations
under Environmental Laws, and no additional permits or other governmental
authorizations under Environmental Laws, will be required to permit the Company
and its subsidiaries or the Surviving Corporation and its subsidiaries, as the
case may be, to be in full compliance with all applicable Environmental Laws
immediately following the transactions contemplated hereby, as conducted by the
Company and its subsidiaries immediately prior to the date hereof.  To the
extent that such transfers or additional permits and other governmental
authorizations are required, the Company and its subsidiaries agree to use its
reasonable best efforts to effect such transfers and obtain such permits and
other governmental authorizations prior to the consummation of the Offer.


                                         -22-

<PAGE>


         (f)  The following terms as used in this Section shall have the
following meanings:

    "Cleanup" means all actions required to:  (1) cleanup, remove, treat or
remediate Hazardous Materials in the indoor or outdoor environment; (2) prevent
the Release of Hazardous Materials so that they do not migrate, endanger or
threaten to endanger public health or welfare of the indoor or outdoor
environment; (3) perform pre-remedial studies and investigations and post-
remedial monitoring and care; or (4) respond to any government requests for
information or documents in any way relating to cleanup, removal, treatment or
remediation or potential cleanup, removal, treatment or remediation of Hazardous
Materials in the indoor or outdoor environment.

    "Environmental Claim" means any claim, action, cause of action,
investigation or notice (written or oral) by any person or entity alleging
potential liability (including, without limitation, potential liability  for
investigatory costs, cleanup costs, governmental response costs, natural
resources damages, property damages, personal injuries, or penalties) arising
out of, based on or resulting from (a) the presence, or Release into the indoor
or outdoor environment, of any Hazardous Materials at any location, whether or
not owned or operated by the Company or any of its subsidiaries or (b)
circumstances forming the basis of any violation, or alleged violation, of any
Environmental Law.

    "Environmental Laws" means all federal, state, local and foreign laws and
regulations, rules, permits, licenses, approvals and orders relating to
pollution or protection of human health or the environment, including without
limitation, laws relating to Releases or threatened Releases of Hazardous
Materials in or into the indoor or outdoor environment (including, without
limitation, ambient air, surface water, ground water, land surface or subsurface
strata) or otherwise relating to the manufacture, processing, distribution, use,
treatment, storage, Release, disposal, transport or handling of Hazardous
Materials and all laws and regulations with regard to recordkeeping,
notification, disclosure and reporting requirements respecting Hazardous
Materials.

    "Hazardous Materials" means all substances defined as Hazardous Substances
under Section 101(14) of the Comprehensive Environmental Response Compensation
and Liability Act, as amended ("CERCLA") except that the term Hazard Materials
shall include petroleum, natural gas, natural gas liquids, liquified natural
gas, synthetic gas, mixtures of any of the above, and constituents of any of the
above which are themselves considered hazardous or toxic.  The term shall also
include any material which is regulated as a hazardous, toxic or otherwise
dangerous material by any state in the United States or by any human health


                                         -23-

<PAGE>

or environmental agency in the United Kingdom or which otherwise may be the
basis for any federal, state, local or foreign government requiring cleanup,
removal, treatment or remediation.

    "Release" means any release, spill, emission, discharge, leaking, pumping,
injection, deposit, disposal, discharge, dispersal, leaching or migration in or
into the indoor or outdoor environment (including, without limitation, ambient
air, surface water, groundwater and land surface or subsurface strata) or into
or out of any property, including the movement of Hazardous Materials through or
in the air, soil, surface water, groundwater or property.

    Section 4.14   INTELLECTUAL PROPERTY.  (a) Schedule 4.14 sets forth a
complete list of all patents, trademarks and service marks issued in the United
States and other material patents owned by the Company.

         (b) Except as set forth on Schedule 4.14 and as otherwise would not
result in a Material Adverse Effect:  (i) the Company and each of its
subsidiaries owns and has the  exclusive right to make, have made, use, sell,
import and offer for sale (in each case, free and clear of any Liens), all
Intellectual Property (as defined below) used in the conduct of its business as
currently conducted; (ii) to the knowledge of the Company, the manufacture, use,
sale, import or offer for sale of any Intellectual Property by the Company and
its subsidiaries does not infringe on or otherwise violate the rights of any
person; (iii) to the knowledge of the Company, no product (or component thereof
or process) used, sold, imported or manufactured by and/or for, or supplied to,
the Company or any of its subsidiaries infringes or otherwise violates the
Intellectual Property of any other person; (iv) to the knowledge of the Company,
no person is challenging, infringing on or otherwise violating any right of the
Company or any of its subsidiaries with respect to any Intellectual Property
owned by and/or licensed to the Company and its subsidiaries; and (v) to the
knowledge of the Company, the Company is not obligated to pay royalties in
respect of any Intellectual Property.  For purposes of this Agreement
"Intellectual Property" shall mean trademarks, service marks, brand names,
certification marks, trade dress, assumed names, trade names and other
indications of origin, the goodwill associated with the foregoing and
registrations in any jurisdiction of, and applications in any jurisdiction to
register, the foregoing, including any extension, modification or renewal of any
such registration or application; inventions, discoveries and ideas, whether
patentable or not in any jurisdiction; patents, applications for patents
(including, without limitation, division, continuations, continuations in part
and renewal applications), and any renewals, extensions or reissues thereof, in
any jurisdiction; nonpublic information,


                                         -24-

<PAGE>

trade secrets and confidential information and rights in any jurisdiction to
limit the use or disclosure thereof by any person; writings and other works,
whether copyrightable or not in any jurisdiction including, without limitation,
products being researched or developed; registrations or applications for
registration of copyrights in any jurisdiction, and any renewals or extensions
thereof; any similar intellectual property or proprietary rights; and any claims
or causes of action arising out of or related to any infringement or
misappropriation of any of the foregoing.

    Section 4.15   INSURANCE.  The coverage provided by the Company's insurance
policies is reasonable in scope and amount compared to similarly situated
companies, except where the failure to be so reasonable in scope and amount
would not have a Material Adverse Effect.

    Section 4.16   PROPERTIES.  The Company and its subsidiaries do not own any
real property.  The Company and its subsidiaries are not parties to any material
real property leases other than the Company's leases with respect to the real
property located in Abingdon, England, Waltham, Massachusetts and Bedford,
Massachusetts, and true and complete copies of instruments setting forth
material terms of these leases have heretofore been furnished to Parent.  Such
leases are valid and binding, and there does not exist any event which, with
notice or lapse of time or both, would constitute a material default under such
leases by the Company.

    Section 4.17   REGULATORY MATTERS.  (a) Except as disclosed in Schedule
4.17 and except as would not, individually or in the aggregate, have a Material
Adverse Effect, to the knowledge of the Company, (i) since December 31, 1995
through the date hereof there have been no written notices, citations or
decisions by any governmental or regulatory body that any product produced,
manufactured, marketed or distributed at any time by the Company or any Company
subsidiary (the "COMPANY PRODUCTS") is defective or fails to meet any applicable
standards promulgated by any such governmental or regulatory body, or any other
governmental or regulatory body, agency or office of any other jurisdiction to
which the Company or any of its subsidiaries is subject, (ii) since December 31,
1995 through the date hereof there have been no recalls, field notifications or
seizures ordered or threatened by the United States Food and Drug Administration
(the "FDA") or any other comparable governmental or regulatory body with respect
to any of the Company Products and (iii) since December 31, 1995 through the
date hereof none of the Company or the Company subsidiaries have received any
warning letter or Section 305 notices from the FDA (or comparable notices from
such other governmental or regulatory bodies).


                                         -25-

<PAGE>

    (b)  Except as set forth in Schedule 4.17 and as would not, individually or
in the aggregate, have a Material Adverse Effect, with respect to each Company
Product: (i) the Company and its subsidiaries have obtained all applicable
approvals, clearances, authorizations, licenses (including site licensures) and
registrations required by United States or foreign governments or government
agencies to permit the manufacturing, distribution, sale (including
reimbursement and pricing), marketing, export, import or human research
(including clinical and non-clinical trials) of such Product (collectively,
"Licenses"); and (ii) the Company and its subsidiaries are in full compliance
with all terms and conditions of each License in each country in which such
Company Product is marketed, and with all requirements pertaining to the
manufacturing (including current good manufacturing practices), distribution,
sale (including reimbursement and pricing), marketing, export, import or human
research (including good laboratory practices and clinical and non-clinical
trials) of such Company Product which is not required to be the subject of a
License.

    Section 4.18   LABOR MATTERS.  Neither the Company nor any of its
subsidiaries is a party to any collective bargaining or other labor union
contract applicable to persons employed by the Company or any of its
subsidiaries, no collective bargaining agreement is being negotiated by the
Company or any of its subsidiaries and the Company has no knowledge of any
activities or proceedings of any labor union to organize any of their respective
employees.  There is no labor dispute, strike or work stoppage against the
Company or any of its subsidiaries pending or, to the Company's knowledge,
threatened.

    Section 4.19   VOTING REQUIREMENTS.  The affirmative vote of a majority of
the outstanding shares of Common Stock and Class B Common Stock approving this
Agreement is the only vote of the holders of any class or series of Company
Securities necessary to approve this Agreement and the transactions contemplated
by this Agreement.  Pursuant to a stockholders' agreement with the J.P. Morgan
Capital Corporation, the holder all of the issued and outstanding shares of the
Class B Common Stock ("Morgan"), Morgan is required to vote its shares of Class
B Common Stock in the same manner and proportion as the Common Stock is voted
with respect to approval of this Agreement and the transactions contemplated by
this Agreement.

    Section 4.20   STATE TAKEOVER LAWS.  The Board has approved the transactions
contemplated hereby so as to render inapplicable to such transactions, 
including, without limitation, the Offer and the Merger, the restrictions on 
business combinations contained in Chapter 110F of Massachusetts Law.  The 
provisions of Chapter 110D of Massachusetts Law are inapplicable to the Company,
the Offer and the Merger and the Offer and the Merger


                                         -26-

<PAGE>

are exempt from the requirements of any other "moratorium," "control share,"
"fair price," or other anti-takeover laws or regulations of any state.  The
Company has taken all steps necessary irrevocably to exempt the transactions
contemplated by this Agreement from any applicable provisions of the Company's
Restated Articles of Organization and By-Laws which would have the effect of
delaying, preventing or materially reducing the expected benefits to Parent or
Acquisition of the transactions contemplated by this Agreement.

                                      ARTICLE V

               REPRESENTATIONS AND WARRANTIES OF PARENT AND ACQUISITION

    Each of Parent and Acquisition represents and warrants to the Company as
follows:

    Section 5.1    ORGANIZATION.  Each of Parent and Acquisition is a
corporation duly organized, validly existing and in good standing under the laws
of the state of its incorporation and has all requisite corporate power and
authority to own, lease and operate its properties and to carry on its business
as now being conducted, except where the failure to be so organized, existing
and in good standing or to have such power and authority would not reasonably be
likely to prevent or materially delay the consummation of the Offer or the
Merger.

    Section 5.2    AUTHORITY RELATIVE TO THIS AGREEMENT.  Each of Parent and
Acquisition has all necessary corporate power and authority to execute and
deliver this Agreement, to perform its obligations hereunder and to consummate
the transactions contemplated hereby.  The execution, delivery and performance
of this Agreement and the consummation of the transactions contemplated hereby
have been duly and validly authorized by the boards of directors of Acquisition
and Parent and by Parent as the sole stockholder of Acquisition, and no other
corporate proceedings on the part of Parent or Acquisition are necessary to
authorize this Agreement or to consummate the transactions so contemplated.
This Agreement has been duly and validly executed and delivered by each of
Parent and Acquisition and constitutes a legal, valid and binding agreement of
each of Parent and Acquisition, enforceable against each of Parent and
Acquisition in accordance with its terms.

    Section 5.3    NON-CONTRAVENTION; REQUIRED FILINGS AND CONSENTS.  (a) The
execution, delivery and performance by Parent and Acquisition of this Agreement
and the consummation of the transactions contemplated hereby (including the
Merger) do not and will not (i) contravene or conflict with the Certificate of
Incorporation or By-Laws of Parent or Acquisition; (ii) assuming that all
consents, authorizations and approvals contemplated by


                                         -27-

<PAGE>

subsection (b) below have been obtained and all filings described therein have
been made, contravene or conflict with or constitute a violation of any
provision of any law, regulation, judgment, injunction, order or decree binding
upon or applicable to Parent or Acquisition or any of their respective
properties; (iii) conflict with, or result in the breach or termination of any
provision of or constitute a default (with or without the giving of notice or
the lapse of time or both) under, or give rise to any right of termination,
cancellation, or loss of any benefit to which Parent or Acquisition is entitled
under any provision of any agreement, contract, license or other instrument
binding upon Parent, Acquisition or any of their respective properties, or allow
the acceleration of the performance of, any obligation of Parent or Acquisition
under any indenture, mortgage, deed of trust, lease, license, contract,
instrument or other agreement to which Parent or Acquisition is a party or by
which Parent or Acquisition or any of their respective assets or properties is
subject or bound; or (iv) result in the creation or imposition of any Lien on
any asset of Parent or Acquisition, except in the case of clauses (ii), (iii)
and (iv) for any such contraventions, conflicts, violations, breaches,
terminations, defaults, cancellations, losses, accelerations and Liens which,
individually or in the aggregate, would not reasonably be likely to prevent or
materially delay the consummation of the Offer or the Merger.

         (b)  The execution, delivery and performance by Parent and Acquisition
of this Agreement and the consummation of the transactions contemplated hereby
(including the Merger) by Parent and Acquisition require no action by or in
respect of, or filing with, any governmental body, agency, official or authority
(whether domestic, foreign or supranational) other than (i) the filing of
articles of merger in accordance with Massachusetts Law; (ii) compliance with
any applicable requirements of the HSR Act; (iii) compliance with any applicable
requirements of the Exchange Act and state securities, takeover and Blue Sky
laws; and (iv) such actions or filings which, if not taken or made, would not,
individually or in the aggregate, reasonably be likely to prevent the
consummation of the Offer or the Merger.

    Section 5.4    OFFER DOCUMENTS; SCHEDULE 14D-9; PROXY STATEMENT.  Neither
the Offer Documents, nor any of the information provided by Parent or
Acquisition and/or by their auditors, legal counsel, financial advisors or other
consultants or advisors specifically for use in the Schedule 14D-9 shall, on the
respective dates the Offer Documents, the Schedule 14D-9 or any supplements or
amendments thereto are filed with the SEC or on the date first published, sent
or given to the Company's stockholders, as the case may be, contain any untrue
statement of a material fact or omit to state any material fact required to be
stated therein or necessary in order to make the statements


                                         -28-

<PAGE>

therein, in light of the circumstances under which they were made, not
misleading.  Notwithstanding the foregoing, neither Parent nor Acquisition makes
any representation or warranty with respect to any information provided by the
Company and/or by its auditors, legal counsel, financial advisors or other
consultants or advisors specifically for use in the Offer Documents.  None of
the information provided by Parent or Acquisition and/or by their auditors,
attorneys, financial advisors or other consultants or advisors specifically for
use in the Proxy Statement shall, at the time filed with the SEC, at the time
mailed to the Company's stockholders, at the time of the Stockholders' Meeting
or at the Effective Time, contain any untrue statement of a material fact or
omit to state any material fact required to be stated therein or necessary in
order to make the statements therein, in light of the circumstances under which
they are made, not misleading.  The Offer Documents will comply as to form in
all material respects with the provisions of the Exchange Act and the rules and
regulations thereunder.

    Section 5.5    NO PRIOR ACTIVITIES.  Since the date of its incorporation,
Acquisition has not engaged in any activities other than in connection with or
as contemplated by this Agreement or in connection with arranging any financing
required to consummate the transactions contemplated hereby.

    Section 5.6    FINANCING.  Acquisition has or will have available to it all
funds necessary to satisfy its obligations hereunder, including, without
limitation, the obligation to pay the Per Share Amount pursuant to the Offer and
the Merger Consideration pursuant to the Merger and to pay all related fees and
expenses in connection with the Offer and the Merger.


                                      ARTICLE VI

                                      COVENANTS

    Section 6.1    CONDUCT OF BUSINESS OF THE COMPANY.  Except as otherwise
expressly provided in this Agreement, during the period from the date hereof to
the time Acquisition's designees are elected as directors of the Company
pursuant to Section 1.3, the Company and its subsidiaries will each conduct its
operations in the ordinary course of business consistent with past practice, and
the Company and its subsidiaries will each use its reasonable best efforts to
preserve intact its business organization, to keep available the services of its
officers and employees and to maintain existing relationships with licensors,
licensees, suppliers, contractors, distributors, customers and others having
business relationships with it.  Without limiting the generality of the
foregoing, and except as otherwise expressly provided in this Agreement, prior
to the Effective Time, neither the Company


                                         -29-

<PAGE>

nor any of its subsidiaries will, without the prior written consent of
Acquisition:

         (a)  amend or propose to amend its articles of organization or by-laws
or equivalent organizational documents, or increase or propose to increase the
number of directors of the Company;

         (b)  authorize for issuance, issue, sell, deliver or agree or commit
to issue, sell or deliver (whether through the issuance or granting of options,
warrants, commitments, subscriptions, rights to purchase or otherwise) any stock
of any class or any other securities or equity equivalents (including, without
limitation, stock appreciation rights), except as required by option agreements
and option plans as in effect as of the date hereof, or amend any of the terms
of any such securities or agreements outstanding as of the date hereof;

         (c)  split, combine or reclassify any shares of its capital stock,
declare, set aside or pay any dividend or other distribution (whether in cash,
stock, or property or any combination thereof) in respect of its capital stock,
or redeem, repurchase or otherwise acquire any of its securities or any
securities of its subsidiaries;

         (d)  (i) except in the ordinary course of business consistent with
past practice, incur any indebtedness for borrowed money or issue any debt
securities or, assume, guarantee or endorse the obligations of any other person;
(ii) make any loans, advances or capital contributions to, or investments in,
any other person (other than to wholly owned subsidiaries of the Company); (iii)
pledge or otherwise encumber shares of capital stock of the Company or any of
its subsidiaries; or (iv) except in the ordinary course of business consistent
with past practice, mortgage or pledge any of its assets, tangible or
intangible, or create or suffer to exist any Lien thereupon;

         (e)  enter into, adopt or (except as may be required by law) amend or
terminate any bonus, profit sharing, compensation, severance, termination, stock
option, stock appreciation right, restricted stock, performance unit, stock
equivalent, stock purchase agreement, pension, retirement, deferred
compensation, employment, severance or other employee benefit agreement, trust,
plan, fund or other arrangement for the benefit or welfare of any director,
officer or employee, or (except, in the case of employees who are not officers
or directors, for normal compensation increases in the ordinary course of
business consistent with past practice that, in the aggregate, do not result in
a material increase in benefits or compensation expense to the Company) increase
in any manner the compensation or benefits of any director, officer or employee
or pay any benefit


                                         -30-

<PAGE>

not required by any plan or arrangement as in effect as of the date hereof
(including, without limitation, the granting of stock options, restricted stock,
stock appreciation rights or performance units);

         (f)  acquire, sell, lease, license, encumber, transfer or dispose of
any assets outside the ordinary course of business consistent with past practice
or any assets which in the aggregate are material to the Company and its
subsidiaries, taken as a whole, or enter into any contract, agreement,
commitment or transaction outside the ordinary course of business consistent
with past practice;

         (g)  except as may be required as a result of a change in law or in
generally accepted accounting principles, change any of the accounting
principles or practices used by it;

         (h)  (i) acquire (by merger, consolidation, or acquisition of stock or
assets) any corporation, partnership or other business organization or division
thereof; (ii) authorize any new capital expenditure or expenditures which, was
not reflected in the capital budget previously furnished to Parent by the
Company; (iii) settle any litigation for amounts in excess of $500,000
individually or $1,000,000 in the aggregate; or (iv) enter into or amend any
contract, agreement, commitment or arrangement with respect to any of the
foregoing;

         (i)  make any tax election or settle or compromise any material Tax
liability;

         (j)  pay, discharge or satisfy any claims, liabilities or obligations
(absolute, accrued, asserted or unasserted, contingent or otherwise), other than
the payment, discharge or satisfaction in the ordinary course of business
consistent with past practice or in accordance with their terms, of liabilities
reflected or reserved against in the consolidated financial statements (or the
notes thereto) of the Company and its consolidated subsidiaries or incurred in
the ordinary course of business consistent with past practice, except where such
action would not result in a Material Adverse Effect;

         (k)  enter into any agreement providing for the acceleration of
payment or performance or other consequence as a result of a change in control
of the Company;

         (l)  (i) enter into any agreement providing for any license, sale,
assignment or otherwise transfer any patent rights or grant any covenant not to
sue with respect to any of its patent rights or (ii) enter into any agreements 
providing for any license, sale or assignment or otherwise transfer any 
Intellectual Property or grant any covenant not to sue with 


                                         -31-

<PAGE>

respect to its Intellectual Property, except if such agreement, assignment or 
transfer would not have a Material Adverse Effect; or

         (m)  take, or agree in writing or otherwise to take, any of the
actions described above in Section 6.1 or any action which would make any of the
representations or warranties of the Company contained in this Agreement untrue
or incorrect or would result in any of the conditions to the Offer not being
satisfied.

         Notwithstanding anything to the contrary contained herein, the Company
may adopt a shareholder rights plan, issue rights thereunder and issue
securities upon exercise of such rights; PROVIDED, HOWEVER, that such rights
plan exempts the Offer and the Merger from the events which trigger the exercise
of such rights.

    Section 6.2    ACCESS TO INFORMATION.  (a) Subject to applicable law and
the agreements set forth in Section 6.2(b), between the date hereof and the
Effective Time, the Company will give each of Parent and Acquisition and their
counsel, financial advisors, auditors, and other authorized representatives
reasonable access to all employees, plants, offices, warehouses and other
facilities and to all books and records of the Company and its subsidiaries,
will permit each of Parent and Acquisition and their respective counsel,
financial advisors, auditors and other authorized representatives to make such
inspections as Parent or Acquisition may reasonably require and will cause the
Company's officers or representatives and those of its subsidiaries to furnish
promptly to Parent or Acquisition or their representatives such financial and
operating data and other information with respect to the business and properties
of the Company and any of its subsidiaries as Parent or Acquisition may from
time to time request.  No investigation pursuant to this Section 6.2 shall
affect any representations or warranties of the parties herein or the conditions
to the obligations of the parties hereunder.

         (b)  Parent and Acquisition agree to be bound by the confidentiality
agreement dated March 13, 1996 (the "Confidentiality Agreement"), among the
Company and Parent as if the references to Parent therein were to Acquisition.
Notwithstanding any provision of the Confidentiality Agreement, Parent and
Acquisition may (i) enter into this Agreement, (ii) acquire Shares pursuant to
the Offer and the Merger and (iii) make such disclosures in connection with the
Offer and the Offer Documents as Parent and Acquisition may determine in their
reasonable discretion is required by applicable law.

    Section 6.3    REASONABLE BEST EFFORTS.  Subject to the terms and
conditions herein provided, each of the parties hereto agrees


                                         -32-

<PAGE>

to use its reasonable best efforts to take, or cause to be taken, all actions,
and to do, or cause to be done, all things reasonably necessary, proper or
advisable under applicable laws and regulations to consummate and make effective
the transactions contemplated by this Agreement.  Without limiting the
generality of the foregoing, Parent, Acquisition and the Company shall cooperate
with one another (i) in the preparation and filing of the Offer Documents, the
Schedule 14D-9, the Proxy Statement and any required filings under the HSR Act
and the other laws referred to in Sections 4.4(b) and 5.3(b); (ii) in
determining whether action by or in respect of, or filing with, any governmental
body, agency, official or authority (either domestic or foreign) is required,
proper or advisable or any actions, consents, waivers or approvals are required
to be obtained from parties to any contracts, in connection with the
transactions contemplated by this Agreement; and (iii) in seeking timely to
obtain any such actions, consents and waivers and to make any such filings.  In
case at any time after the Effective Time any further action is necessary or
desirable to carry out the purposes of this Agreement, the proper officers and
directors of each party hereto shall take all such necessary action.

    Section 6.4    PUBLIC ANNOUNCEMENTS.  Parent and Acquisition, on the one
hand, and the Company, on the other hand, will consult with each other before
issuing any press release or otherwise making any public statements with respect
to the transactions contemplated by this Agreement and shall not issue any such
press release or make any such public statement prior to such consultation,
except as may be required by applicable law or by applicable rules of any
securities exchange or the Nasdaq National Market.  The initial joint
announcement of the transactions contemplated by this Agreement shall be in the
form attached hereto as Annex B.

    Section 6.5    INDEMNIFICATION.  (a) Parent shall cause the Surviving
Corporation to keep in effect the provisions in its Articles of Organization and
By-Laws containing the provisions with respect to exculpation of director and
officer liability and indemnification set forth in the Restated Articles of
Organization and Amended and Restated By-Laws of the Company on the date of this
Agreement to the fullest extent permitted under applicable law, which provisions
shall not be amended, repealed or otherwise modified except as required by
applicable law or except to make changes permitted by applicable law that would
enlarge the exculpation or rights of indemnification thereunder.

    (b)  From and after the Effective Time, Parent hereby agrees to guarantee
and to cause the Surviving Corporation to perform all of its obligations under
the Restated Articles of Organization and By-Laws of the Company with respect to
indemnification.


                                         -33-

<PAGE>

    (c)  Parent shall cause the Surviving Corporation to use its reasonable
best efforts to maintain in effect for five years from the Effective Time, if
available, the coverage provided by the current directors' and officers'
liability insurance policies maintained by the Company (provided that the
Surviving Corporation may substitute therefor policies of at least the same
coverage containing terms and conditions which are not materially less
favorable) with respect to matters occurring prior to the Effective Time;
PROVIDED, HOWEVER, that nothing contained herein shall require the Surviving
Corporation to incur any annual premium in excess of 200% of the last annual
aggregate premium paid prior to the date of this Agreement for all current
directors' and officers' liability insurance policies maintained by the Company
which the Company represents and warrants to be $278,000 (the "Current
Premium").  If such premiums for such insurance would at any time exceed 200% of
the Current Premium, then the Surviving Corporation shall cause to be maintained
policies of insurance which, in the Surviving Corporation's good faith
determination, provide the maximum coverage available at an annual premium equal
to 200% of the Current Premium.

    Section 6.6    NOTIFICATION OF CERTAIN MATTERS.  The Company shall give
prompt notice to Parent or Acquisition, and Parent or Acquisition shall give
prompt notice to the Company, as the case may be, of (i) the occurrence, or non-
occurrence, of any event the respective occurrence, or non-occurrence, of which
would be likely to cause any representation or warranty contained in this
Agreement to be untrue or inaccurate and (ii) any failure of the Company, Parent
or Acquisition, as the case may be, to comply with or satisfy any covenant,
condition or agreement to be complied with or satisfied by it hereunder;
PROVIDED, that the delivery of any notice pursuant to this Section 6.6 shall not
limit or otherwise affect the remedies available hereunder to the party
receiving such notice.

    Section 6.7    TERMINATION OF STOCK PLANS.  Prior to the consummation of
the Offer, the Board (or, if appropriate, any committee thereof) shall adopt
such resolutions or take such other actions as are required to ensure that,
following the Effective Time, no participant in any stock, stock option, stock
appreciation or other benefit plan of the Company or any of its subsidiaries or
any holder of any Option shall have any right thereunder to acquire any capital
stock of the Surviving Corporation or any subsidiary thereof.

    Section 6.8    NO SOLICITATION.  (a) The Company will immediately cease any
existing discussions or negotiations with any third parties conducted prior to
the date hereof with respect to any Acquisition Proposal (as defined below).
The Company shall not, directly or indirectly, through any officer, director,
employee, representative or agent or any of its subsidiaries, (i) 


                                         -34-

<PAGE>

solicit, initiate, continue or encourage any inquiries, proposals or offers that
constitute, or could reasonably be expected to lead to, a proposal or offer for
a merger, consolidation, business combination, sale of substantial assets, sale
of shares of capital stock (including, without limitation, by way of a tender
offer) or similar transactions involving the Company or any of its subsidiaries,
other than the transactions contemplated by this Agreement (any of the foregoing
inquiries or proposals being referred to in this Agreement as an "Acquisition
Proposal"), (ii) solicit, initiate, continue or engage in negotiations or 
discussions concerning, or provide any non-public information or data to any 
person or entity relating to, any Acquisition Proposal, or (iii) agree to, 
approve or recommend any Acquisition Proposal; PROVIDED, that nothing contained
in this Section 6.8 shall prevent the Company from, prior to the purchase by 
Acquisition of Shares pursuant to the Offer, furnishing non-public information 
or data to, or entering into discussions or negotiations with, any person in 
connection with an unsolicited Acquisition Proposal by such person or 
recommending an unsolicited Acquisition Proposal to the stockholders of the 
Company, if and only to the extent that (1) the Company's directors determine in
good faith, after receiving advice of its independent counsel, that such action
is required for the discharge of their fiduciary duties to stockholders under 
applicable law and (2) prior to furnishing such nonpublic information to, or 
entering into discussions or negotiations with, such person, the Company 
receives from such person an executed confidentiality agreement with terms no 
less favorable, taken as a whole, to the Company than those contained in the 
Confidentiality Agreement, but which confidentiality agreement shall not include
any provision calling for any exclusive right to negotiate with the Company, and
(3) the Company advises Parent of all such nonpublic information  delivered to 
such person concurrently with its delivery to the requesting party.

         (b)  The Company shall notify Parent immediately (and in no event
later than 24 hours) after receipt by the Company of any Acquisition Proposal or
any request for non-public information in connection with an Acquisition
Proposal or for access to the properties, books or records of the Company by any
person or entity that informs the Company that it is considering making, or has
made, an Acquisition Proposal.


                                     ARTICLE VII

                       CONDITIONS TO CONSUMMATION OF THE MERGER

    Section 7.1    CONDITIONS TO EACH PARTY'S OBLIGATION TO EFFECT THE MERGER.
The respective obligations of each party


                                         -35-

<PAGE>

hereto to effect the Merger is subject to the satisfaction at or prior to the
Effective Time of the following conditions:

         (a)  Acquisition shall have purchased Shares pursuant to the Offer;

         (b)  if required by Massachusetts Law, this Agreement shall have been
adopted by the affirmative vote of the stockholders of the Company by the
requisite vote in accordance with Massachusetts Law;

         (c)  there shall not be in effect any order, decree or ruling or other
action restraining, enjoining or otherwise prohibiting the Merger, which order,
decree, ruling or action shall have been issued or taken by any court of
competent jurisdiction or other governmental body located or having jurisdiction
within the United States or any country or economic region in which the Company
or any of its subsidiaries or Parent or any of its affiliates, directly or
indirectly, has material assets or operations; and

         (d)  any waiting period applicable to the Merger under the HSR Act
shall have terminated or expired.


                                     ARTICLE VIII

                       TERMINATION; EXPENSES; AMENDMENT; WAIVER

    Section 8.1    TERMINATION.  This Agreement may be terminated and the
Merger may be abandoned at any time prior to the Effective Time, notwithstanding
approval thereof by the stockholders of the Company:

         (a)  by mutual written consent of Parent, Acquisition and the Company;

         (b)  by Parent or the Company if any court of competent jurisdiction
or other governmental body located or having jurisdiction within the United
States or any country or economic region in which the Company or any of its
subsidiaries or Parent or any of its affiliates, directly or indirectly, has
material assets or operations, shall have issued an order, decree or ruling or
taken any other action restraining, enjoining or otherwise prohibiting the Offer
or the Merger and such order, decree, ruling or other action shall have become
final and nonappealable;

         (c)  by Parent or the Company if Acquisition shall have (A) terminated
the Offer or (B) failed to accept for purchase and pay for Shares pursuant to
the Offer by June 30, 1996 unless


                                         -36-

<PAGE>

Acquisition shall have failed to accept for purchase and pay for Shares pursuant
to the Offer as the result of the receipt by the Company of an Acquisition
Proposal or as a result of a failure of the applicable waiting period under the
HSR Act to expire or the failure to obtain any necessary governmental or
regulatory approvals, in which case, if Acquisition shall have failed to accept
for purchase and pay for Shares pursuant to the Offer by September 30, 1996;
PROVIDED, that the right to terminate this Agreement under the foregoing clauses
(A) or (B) shall not be available to any party whose failure to fulfill any
obligation under this Agreement has been the cause or resulted in any of the
circumstances described in such clauses;

         (d)  by either Parent or the Company if, prior to the purchase of
Shares pursuant to the Offer, the other party shall have failed to comply in all
material respects with any of its covenants or agreements contained in this
Agreement required to be complied with prior to the date of such termination,
which failure to comply has not been cured within twenty business days following
receipt by such other party of written notice of such failure to comply;
PROVIDED, HOWEVER, that, if such breach is curable by the breaching party
through the exercise of the breaching party's best efforts and for so long as
the breaching party continues to exercise such best efforts, the nonbreaching
party may not terminate this Agreement under this Section 8.1(d);

         (e)  by either Parent or the Company if, prior to the purchase of
Shares pursuant to the Offer, there has been (i) a breach in any material
respect by the other party (in the case of Parent, including any material breach
by Acquisition) of any representation or warranty that is not qualified as to
materiality which has the effect of making such representation or warranty not
true and correct in all material respects or (ii) a breach by the other party
(in the case of Parent, including any material breach by Acquisition) of any
representation that is qualified as to materiality, in each case which breach
has not been cured within twenty business days following receipt by the
breaching party of written notice of the breach; PROVIDED, HOWEVER, that, if
such breach is curable by the breaching party through the exercise of the
breaching party's best efforts and for so long as the breaching party continues
to exercise such best efforts, the nonbreaching party may not terminate this
Agreement under this Section 8.1(e);

         (f)  by either Parent or the Company, not sooner than the third
business day after the Company's notice to Parent of the Company's receipt of an
Acquisition Proposal if the Board reasonably determines that such Acquisition
Proposal constitutes a Superior Proposal; or



                                         -37-

<PAGE>

         (g)       by Parent if the Board shall have withdrawn or modified in a
manner adverse to Parent or Acquisition its approval of the Offer, this
Agreement, the Merger, its recommendation that the Company's stockholders accept
the Offer and the Company shall have entered into an agreement providing for an
Acquisition Proposal or the Board shall have resolved to do any of the
foregoing.

              "SUPERIOR PROPOSAL" shall mean a bona fide proposal or offer made
by a third party to acquire the Company pursuant to a tender or exchange offer,
a merger, consolidation, acquisition of a majority of the Shares or other
business combination or a sale of all or substantially all of the assets of the
Company and its subsidiaries on terms which the Board determines in good faith
(after consultation with independent financial advisors and counsel) to be more
favorable to the Company and to its stockholders than the transactions
contemplated hereby.

    Section 8.2    EFFECT OF TERMINATION.  (a)  If this Agreement is terminated
pursuant to Section 8.1(f) or Section 8.1(g), the Company shall pay Parent a
non-refundable fee of $17,500,000, which amount shall be payable by wire
transfer of same day funds within two business days after the date this
Agreement is so terminated.

         (b) In the event of the termination and abandonment of this Agreement
pursuant to Section 8.1, this Agreement shall forthwith become void and have no
effect, other than the provisions of this Section 8.2 and Section 8.3.  No
termination of this Agreement and nothing contained in this Section 8.2 shall
relieve any party from liability for any breach of this Agreement.

    Section 8.3    FEES AND EXPENSES.  Subject to Section 8.2(a) above, each
party shall bear its own expenses and costs in connection with this Agreement
and the transactions contemplated hereby.

    Section 8.4    AMENDMENT.  Subject to Section 1.3(c), this Agreement may be
amended by action taken by the Company, Parent and Acquisition at any time
before or after adoption of the Merger by the stockholders of the Company (if
required by applicable law) but, after any such approval, no amendment shall be
made which decreases the Merger Consideration or changes the form thereof or
which adversely affects the rights of the Company's stockholders hereunder
without the approval of such stockholders.  This Agreement may not be amended
except by an instrument in writing signed on behalf of each of the parties
hereto.


                                         -38-

<PAGE>

    Section 8.5    EXTENSION; WAIVER.  Subject to Section 1.3(c), at any time
prior to the Effective Time, the Company, on the one hand, and Parent and
Acquisition, on the other hand, may (i) extend the time for the performance of
any of the obligations or other acts of the other party, (ii) waive any
inaccuracies in the representations and warranties of the other party contained
herein or in any document, certificate or writing delivered pursuant hereto, or
(iii) waive compliance by the other party with any of the agreements or
conditions contained herein.  Any agreement on the part of any party hereto to
any such extension or waiver shall be valid only if set forth in an instrument
in writing signed on behalf of such party.  The failure of any party hereto to
assert any of its rights hereunder shall not constitute a waiver of such rights.


                                      ARTICLE IX

                                    MISCELLANEOUS

    Section 9.1    NONSURVIVAL OF REPRESENTATIONS AND WARRANTIES.  The
representations and warranties made herein shall not survive beyond the
Effective Time. The covenants and agreements herein shall survive in accordance
with their respective terms.

    Section 9.2    ENTIRE AGREEMENT; ASSIGNMENT.  This Agreement, and the
Confidentiality Agreement (i) constitute the entire agreement among the parties
hereto with respect to the subject matter hereof and supersede all other prior
agreements and understandings, both written and oral, among the parties with
respect to the subject matter hereof and (ii) shall not be assigned by operation
of law or otherwise; PROVIDED that Acquisition may assign its rights and
obligations in whole or in part to Parent or any subsidiary of Parent, but no
such assignment shall relieve Acquisition of its obligations hereunder if such
assignee does not perform such obligations.

    Section 9.3    NOTICES.  All notices, requests, claims, demands and other
communications hereunder shall be in writing and shall be given (and shall be
deemed to have been duly given upon receipt) by delivery in person, by facsimile
or by registered or certified mail (postage prepaid, return receipt requested),
to the other party as follows:

    if to Parent or Acquisition:


         Abbott Laboratories
         100 Abbott Park Road
         Abbott Park, Illinois  60064


                                         -39-

<PAGE>

         Fax:  847-937-4604
         Attention:  President, Diagnostics
                      Division
         and,

         Fax:  847-938-6277
         Attention:  General Counsel

    with copies to:

         Mayer, Brown & Platt
         190 South LaSalle Street
         Chicago, Illinois  60603-3441
         Fax:  312-701-7711
         Attention:  Robert A. Helman and Scott J. Davis


    if to the Company:

         MediSense, Inc.
         266 Second Avenue
         Waltham, Massachusetts  02154
         Fax:  617-890-8637
         Attention:  General Counsel


    with a copy to:

         Shearman & Sterling
         599 Lexington Avenue
         New York, New York  10022
         Fax:  212-848-7179/80/81/82
         Attention:  Peter D. Lyons

or to such other address as the person to whom notice is given may have
previously furnished to the other in writing in the manner set forth above.

    Section 9.4    GOVERNING LAW.  This Agreement shall be governed by and
construed in accordance with the laws of the Commonwealth of Massachusetts
applicable to contracts executed in and to be performed in that State.

    Section 9.5    PARTIES IN INTEREST.  Except for Section 6.5, which shall
inure to the benefit of the persons identified therein, this Agreement shall be
binding upon and inure solely to the benefit of each party hereto and its
successors and permitted assigns, and nothing in this Agreement, express or
implied, is intended to or shall confer upon any other person any rights,
benefits or remedies of any nature whatsoever under or by reason of this
Agreement.


                                         -40-

<PAGE>

    Section 9.6    SPECIFIC PERFORMANCE.  The parties hereto agree that
irreparable damage would occur in the event any provision of this Agreement was
not performed in accordance with the terms hereof and that the parties shall be
entitled to specific performance of the terms hereof, in addition to any other
remedy at law or in equity.

    Section 9.7    SEVERABILITY.  The provisions of this Agreement shall be
deemed severable and the invalidity or unenforceability of any provision shall
not affect the validity and enforceability of the other provisions hereof.  If
any provision of this Agreement, or the application thereof to any person or
entity or any circumstance, is invalid or unenforceable, (a) a suitable and
equitable provision shall be substituted therefor in order to carry out, so far
as may be valid and enforceable, the intent and purpose of such invalid and
unenforceable provision and (b) the remainder of this Agreement and the
application of such provision to other persons, entities or circumstances shall
not be affected by such invalidity or unenforceability, nor shall such
invalidity or unenforceability affect the validity or enforceability of such
provision, or the application thereof, in any other jurisdiction.

    Section 9.8    DESCRIPTIVE HEADINGS.  The descriptive headings herein are
inserted for convenience of reference only and are not intended to be part of or
to affect the meaning or interpretation of this Agreement.

    Section 9.9    CERTAIN DEFINITIONS.  For purposes of this Agreement, the
term:

         (a)  "affiliate" of a person means a person that directly or
indirectly, through one or more intermediaries, controls, is controlled by, or
is under common control with, the first mentioned person;

         (b)  "associate" of a person means a corporation or organization of
which such person is an officer or partner or is, directly or indirectly, the
beneficial owner of 10 percent or more of any class of equity securities or any
person who is a director or officer of such person or any of its parents or
subsidiaries;

         (c)  "business day" shall mean any day other than a Saturday, Sunday
or federal holiday.

         (d)  "control" (including the terms "controlled by" and "under common
control with") means the possession, directly or indirectly or as trustee or
executor, of the power to direct or cause the direction of the management
policies of a person,


                                         -41-

<PAGE>

whether through the ownership of stock, as trustee or executor, by contract or
credit arrangement or otherwise;

         (e)  "generally accepted accounting principles" shall mean the
generally accepted accounting principles set forth in the opinions and
pronouncements of the Accounting Principles Board of the American Institute of
Certified Public Accountants and statements and pronouncements of the Financial
Accounting Standards Board or in such other statements by such other entity as
may be approved by a significant segment of the accounting profession in the
United States, in each case applied on a basis consistent with the manner in
which the audited financial statements for the fiscal year of the Company ended
March 31, 1995 were prepared;

         (f)  "knowledge" or "known" means, with respect to any matter in
question, if the executive officers of the Company or Parent, as the case may
be, have actual knowledge of such matter;

         (g)  "person" means an individual, corporation, partnership,
association, trust, unincorporated organization, other entity or group (as
defined in Section 13(d)(3) of the Exchange Act); and

         (h)  "subsidiary" or "subsidiaries" of any person means any
corporation, partnership, joint venture or other legal entity of which such
person (either alone or through or together with any other subsidiary), owns,
directly or indirectly, 50% or more of the stock or other equity interests the
holder of which is generally entitled to vote for the election of the board of
directors or other governing body of such corporation, partnership, joint
venture or other legal entity.

    Section 9.10   COUNTERPARTS.  This Agreement may be executed in two or more
counterparts, each of which shall be deemed to be an original, but all of which
shall constitute one and the same agreement.


                                         -42-

<PAGE>

    IN WITNESS WHEREOF, each of the parties has caused this Agreement to be
executed on its behalf by its representatives thereunto duly authorized, all as
of the day and year first above written.


[CORPORATE SEAL]                       ABBOTT LABORATORIES


Attest by:                             By:
          ----------------------           --------------------------
          Title:                           Title:


Attest by:                             By:
          ----------------------           --------------------------
          Title:                           Title:


[CORPORATE SEAL]                       AAC ACQUISITION, INC.


Attest by:                             By:
          ----------------------           --------------------------
          Title:                           Title:


Attest by:                             By:
          ----------------------           --------------------------
          Title:                           Title:


[CORPORATE SEAL]                       MEDISENSE, INC.


Attest by:                             By:
          ----------------------           --------------------------
          Title:                           Title:


Attest by:                             By:
          ----------------------           --------------------------
          Title:                           Title:


                                         -43-

<PAGE>

                                                                         ANNEX A


                                   OFFER CONDITIONS

    The capitalized terms used in this Annex A have the meanings set forth in
the attached Agreement, except that the term "Merger Agreement" shall be deemed
to refer to the attached Agreement and the term "Commission" shall be deemed to
refer to the SEC.

    Notwithstanding any other provision of the Offer, Acquisition shall not be
required to accept for payment or, subject to any applicable rules and
regulations of the Commission, including without limitation, Rule 14e-1(c) under
the Exchange Act (relating to Acquisition's obligation to pay for or return
Shares promptly after termination or withdrawal of the Offer), pay for any
Shares tendered pursuant to the Offer, and may postpone the acceptance for
payment or, subject to the restriction referred to above, payment for any Shares
tendered pursuant to the Offer, and may terminate or amend the Offer and not
accept for payment any Shares, if (i) the Minimum Condition shall not have been
satisfied, (ii) any applicable waiting period under the HSR Act shall not have
expired or been terminated, or (iii) compliance of any applicable waiting period
requirements of any laws or regulations relating to the regulation of monopolies
or competition in Germany shall not have expired or been terminated; PROVIDED,
that prior to June 30, 1996, (or, if the conditions to the Offer have not been
satisfied prior to June 30, 1996 as the result of the receipt by the Company of
an Acquisition Proposal or as a result of a failure of the applicable waiting
period under the HSR Act to expire or the failure to obtain any necessary
governmental or regulatory approvals, prior to September 30, 1996) Acquisition
shall not terminate the Offer by reason of the nonsatisfaction of any of the
conditions and shall extend the Offer, or (iv) at any time on or after April 4,
1996 and prior to the acceptance for payment of Shares, any of the following
conditions occurs:

         (a)  there shall have been any action or proceeding brought by any
governmental authority before any court, or any order or preliminary or
permanent injunction entered in any action or proceeding before any court or
governmental, administrative or regulatory authority or agency, located or
having jurisdiction within the United States or any other country or economic
region in which the Company or any of its subsidiaries or Parent or any of its
subsidiaries, directly or indirectly, has material assets or operations, or any
statute, rule, regulation, legislation, judgment or order, enacted, entered,
enforced, promulgated, amended, issued or deemed applicable to the Offer or the
Merger by any court, governmental, administrative or regulatory authority or
agency located or


<PAGE>

having jurisdiction within the United States or any other country or economic
region in which the Company or any of its subsidiaries or Parent or any of its
subsidiaries, directly or indirectly, has material assets or operations, which
could result in a Material Adverse Effect have the effect of:  (i) making
illegal, or otherwise directly or indirectly restraining or prohibiting or
imposing material penalties or fines or requiring the payment of material
damages in connection with the making of the Offer, the acceptance for payment
of, payment for, or ownership, directly or indirectly, of some of or all the
Shares by Parent or Acquisition, the consummation of the Offer or the Merger;
(ii) prohibiting or materially limiting the direct or indirect ownership or
operation by the Company or by Parent of all or any material portion of the
business or assets of the Company and its subsidiaries, taken as a whole, or
compelling Parent to dispose of or hold separate all or any material portion of
the business or assets of the Company and its subsidiaries, taken as a whole, as
a result of the transactions contemplated by the Merger Agreement; (iii)
imposing or confirming material limitations on the ability of Parent effectively
directly or indirectly to acquire or hold or to exercise full rights of
ownership of Shares, including, without limitation, the right to vote any Shares
on all matters properly presented to the stockholders of the Company, including,
without limitation, the adoption and approval of the Merger Agreement and the
Merger or the right to vote any shares of capital stock of any subsidiary of the
Company; or (iv) requiring divestiture by Parent or Acquisition, directly or
indirectly, of any Shares; or

         (b)  there shall have occurred (i) any general suspension of trading
in, or limitation on prices for, securities on any securities exchange or in the
over-the-counter market in the United States (other than a shortening of trading
hours or any coordinated trading halt triggered solely as a result of a
specified increase or decrease in a market index), (ii) the declaration of a
banking moratorium or any suspension of payments in respect of banks in the
United States (whether or not mandatory), or (iii) any limitation (whether or
not mandatory), by any United States governmental authority or agency on the
extension of credit by banks or other financial institutions; or

         (c)  the Company shall have breached or failed to perform in any
material respect any of its covenants or agreements under the Merger Agreement;
or

         (d)  any of the representations and warranties of the Company set
forth in the Merger Agreement shall not be true and correct representations and
warranties of the Company which address matters only as of a particular date, as
of such date) except where the failure to be so true and correct would not have
a Material Adverse Effect; or

<PAGE>

         (e)  the Merger Agreement shall have been terminated in accordance
with its terms or the Offer shall have been amended or terminated with the
consent of the Company;

which, in the reasonable judgment of Acquisition in any such case, and
regardless of the circumstances (including any action or omission by
Acquisition) giving rise to any such condition makes it inadvisable to proceed
with such acceptance for payment or payments of Shares.

         The foregoing conditions are for the sole benefit of Acquisition and
may be asserted by Acquisition regardless of the circumstances giving rise to
any such condition or may be waived by Acquisition in whole or in part at any
time or from time to time in its sole discretion.  The failure by Acquisition at
any time to exercise any of the foregoing rights shall not be deemed a waiver of
any such right, the waiver of any such right with respect to particular facts or
circumstances shall not be deemed a waiver with respect to any other facts or
circumstances, and each such right shall be deemed an ongoing right that may be
asserted at any time or from time to time.


<PAGE>

                                   MEDISENSE, INC.
                                  266 SECOND AVENUE
                              WALTHAM, MASSACHUSETTS 02154

                                                                  March 13, 1996

Abbott Laboratories
100 Abbott Park Road
Abbott Park, Illinois  60064-3500

                              CONFIDENTIALITY AGREEMENT

Ladies and Gentlemen:

         In order to evaluate a possible transaction (the "PROPOSED
TRANSACTION") between Abbott Laboratories, an Illinois corporation ("ABBOTT"),
and MediSense, Inc., a Massachusetts corporation (the "COMPANY"), each of Abbott
and the Company may disclose and deliver to the other party, upon execution and
delivery by Abbott and the Company of this letter agreement, certain information
about its properties, employees, finances, businesses and operations (such 
party when disclosing such information being the "DISCLOSING PARTY" and such 
party when receiving such information being the "RECEIVING PARTY").  All such 
information furnished  by the Disclosing Party or its Representatives (as 
defined below), whether furnished before or after the date hereof, whether 
oral or written, and regardless of the manner in which it is furnished, is 
referred to in this letter agreement as "PROPRIETARY INFORMATION".  
Proprietary Information does not include, however, information which (a) is 
or becomes generally available to the public other than as a result of a 
disclosure by the Receiving Party or its Representatives, (b) was available 
to the Receiving Party on a nonconfidential basis prior to its disclosure by 
the Disclosing Party or its Representatives, (c) becomes available to the 
Receiving Party on a nonconfidential basis from a person other than the 
Disclosing Party or its Representatives who is not otherwise bound by a 
confidentiality agreement with the Disclosing Party or any of its 
Representatives, or is otherwise not under an obligation to the Disclosing 
Party or any of its Representatives not to transmit the information to the 
Receiving Party, or (d) has been independently developed by the Receiving 
Party (as evidenced by documentation written prior to the date of disclosure) 
without violating any of its obligations whether under this letter agreement 
or any other agreement or otherwise.  As used in this letter agreement, the 
term "REPRESENTATIVE" means,

<PAGE>

                                          2

as to any person, such person's affiliates and its and their directors,
officers, employees, agents, advisors (including, without limitation, financial
advisors, counsel and accountants) and controlling persons.  As used in this
letter agreement, the term "affiliate" has the meaning ascribed to such term in
Rule 12b-2 of the General Rules and Regulations under the Securities Exchange
Act of 1934, as amended (the "EXCHANGE ACT").  As used in this letter agreement,
the term "person" shall be broadly interpreted to include, without limitation,
any corporation, company, partnership, other entity or individual.

         Subject to the immediately succeeding paragraph, unless otherwise
agreed to in writing by the Disclosing Party, the Receiving Party agrees (a)
except as required by law, to keep all Proprietary Information confidential and
not to disclose or reveal any Proprietary Information to any person other than
its Representatives who are actively and directly participating in the
evaluation of the Proposed Transaction or who otherwise need to know the
Proprietary Information for the purpose of evaluating the Proposed Transaction
and to cause those persons to observe the terms of this letter agreement, (b)
not to use Proprietary Information for any purpose other than in connection with
its evaluation of the Proposed Transaction or the consummation of the Proposed
Transaction and (c) except as required by law or pursuant to a listing agreement
with a national securities exchange or the National Association of Securities
Dealers, Inc., not to disclose to any person (other than those of its
Representatives who are actively and directly participating in the evaluation of
the Proposed Transaction or who otherwise need to know for the purpose of
evaluating the Proposed Transaction and, in the case of its Representatives,
whom it will cause to observe the terms of this letter agreement) the fact that
the Proprietary Information exists or has been made available, the fact that the
Receiving Party is considering the Proposed Transaction or any other transaction
involving the Disclosing Party, or that discussions or negotiations are taking
or have taken place concerning the Proposed Transaction or involving the
Disclosing Party or any term, condition or other fact relating to the Proposed
Transaction or such discussions or negotiations, including, without limitation,
the status thereof.  The Receiving Party will be responsible for any breach of
the terms of this letter agreement by the Receiving Party or any of its
Representatives.

         In the event that the Receiving Party is requested pursuant to, or
required by, applicable law, regulation or stock exchange rule or by legal
process to disclose any Proprietary Information or any other information
concerning the Disclosing Party  or the Proposed Transaction, the Receiving 
Party agrees that it will provide the Disclosing Party with prompt notice of 
such request or requirement in order to enable the Disclosing Party to seek 
an appropriate protective order or other remedy, to consult with the 
Receiving Party with respect to the Disclosing Party taking steps to resist 
or narrow the scope of such request or legal process, or to waive compliance, 
in whole or in part, with the terms of this letter agreement.  In the event 
that no such protective order or other remedy is obtained, or that the 
Disclosing Party waives compliance with the terms of this letter agreement, 
the Receiving Party will furnish only that portion of any Proprietary 
Information which the Receiving Party

<PAGE>

                                          3

is advised by counsel is legally required and will exercise all reasonable
efforts to obtain reliable assurance that confidential treatment will be
accorded any Proprietary Information.

         Each of Abbott and the Company is aware, and each of Abbott and the
Company will advise their respective Representatives who are informed of the
matters that are the subject of this letter agreement, of the restrictions
imposed by the United States securities laws on the purchase or sale of
securities by a person who has received material, non-public information from
the issuer of such securities and on the communication of such information to
any other person when it is reasonably foreseeable that such other person is
likely to purchase or sell such securities in reliance upon such information.

         The Receiving Party acknowledges that neither the Disclosing Party nor
any of its Representatives make any express or implied representation or
warranty as to the accuracy or completeness of any Proprietary Information, and
the Receiving Party agrees that none of such persons shall have any liability to
the Receiving Party or any of its Representatives relating to or arising from
the use of any Proprietary Information by the Receiving Party or its
Representatives or for any errors therein or omissions therefrom.  The Receiving
Party also agrees that it is not entitled to rely on the accuracy or
completeness of any Proprietary Information and that it shall be entitled to
rely solely on such representations and warranties regarding Proprietary
Information as may be made to it in any final agreement relating to the Proposed
Transaction, subject to the terms and conditions of such agreement.

         Each party hereto agrees that, without prior written consent of the
other party, it will not for a period of one year from the date hereof directly
or indirectly solicit for employment or employ any person who is now employed by
the other party and who is identified as a result of any evaluation or otherwise
in connection with the Proposed Transaction; PROVIDED, HOWEVER, that nothing
herein shall prohibit either party from employing any person who initiates
employment discussions with such party without any prior solicitation of such
person by such party.

         If either party hereto determines that it does not wish to proceed
with the Proposed Transaction, it will promptly advise the other party of that
decision.  In such case, or if the Proposed Transaction is not consummated by
Abbott and the Company, each party will promptly return to the other party all
copies of Proprietary Information in its possession or in the possession of any
of its Representatives and will not retain any copies or other reproductions in
whole or in part of such material.  All other documents, memoranda, notes,
summaries, analyses, extracts, compilations, studies or other material
whatsoever prepared by it or any of its Representatives based on the Proprietary
Information will be destroyed and such destruction will be certified in writing
to the other party by an authorized officer supervising such destruction.  All
Proprietary Information will continue to be subject to the terms of this letter
agreement.

         You agree that for a period of one year from the date of this letter
agreement, except as otherwise provided below, neither you nor any of your
affiliates will, without the prior written consent of the Company:

<PAGE>

                                          4

    (a)  acquire, offer to acquire, or agree to acquire, directly or
         indirectly, by purchase or otherwise, any voting securities or direct
         or indirect rights to acquire any voting securities of the Company or
         any subsidiary thereof, or any material assets of the Company or any
         subsidiary or division thereof or of any such successor or controlling
         person;

    (b)  make, or in any way participate, directly or indirectly, in any
         "solicitation" of "proxies" to vote (as such terms are used in the
         rules of the Securities and Exchange Commission), or seek to advise or
         influence any person or entity with respect to the voting of any
         voting securities of the Company;

    (c)  make any public announcement with respect to, or submit a proposal
         for, or offer of (with or without conditions) any extraordinary
         transaction involving the Company or any of its securities or
         material assets;

    (d)  form, join or in any way participate in a "group" as defined in
         Section 13(d)(3) of the Exchange Act, in connection with any of the
         foregoing; or

    (e)  request the Company or any of the Company's Representatives, directly
         or indirectly, to amend or waive any provision of this paragraph,
         except in a manner that is not, and is not intended or required to be,
         disclosed publicly by either party hereto or their respective
         affiliates;

         PROVIDED, HOWEVER, that (a) through (e) above shall be not be binding
         on Abbott if, on or after the date of this Agreement, (A) any person
         or group of persons, other than any person specified in Rule
         13d-1(b)(1)(i) and (ii) under the Exchange Act, acquires beneficial 
         ownership of any equity or voting security of the Company, or any 
         security convertible into or exchangeable for any equity or voting 
         security of the Company, including, without limitation, the Common 
         Stock, par value $.01 per share (the "COMMON STOCK"), of the Company 
         (collectively, the "COMPANY SECURITIES") representing 15% or more of
         the then total outstanding shares of any such class of Company
         Securities, or representing 15% or more of the total outstanding 
         voting interest in the Company; (B) the Company issues or commits to
         issue shares of its Class A Common Stock, par value $.01 per share,
         or any other voting securities, other than the Common Stock or any
         securities convertible into or exchangeable for shares of Common
         Stock; or (C) it has been publicly announced or otherwise publicly
         disclosed that any person or group of persons, other than Abbott 
         or the Company or any of their respective affiliates, proposes to 
         effect or has effected (i) a merger, consolidation or other business 
         combination transaction with the Company, (ii) any sale, lease, 
         exchange, transfer or other disposition of all or substantially all 
         of the assets of the Company and its subsidiaries, taken as a whole,
         (iii) a tender offer or exchange offer for more than 20% of the 
         outstanding shares of any class of Company Securities, or (iv) any

<PAGE>

                                          5

         solicitation of proxies with respect to shares of any class of Company
         Securities by any person or group of persons (other than the Company
         or Abbott or any of its affiliates) with respect to either the
         election of directors or relating to any Acquisition Proposal (each of
         the events set forth in (A), (B) and (C) above are referred to herein
         as an "ACQUISITION PROPOSAL").


         The Company agrees that for a period of 16 days from the date of this
letter agreement, the Company will not, and will use its best efforts to ensure
that its Representatives do not, directly or indirectly, (A) initiate, solicit,
encourage or engage in any discussions with a party other than Abbott or its
Representatives in respect of any Acquisition Proposal, (B) provide any
confidential information in respect of the Company to any person other than
Abbott in connection with any Acquisition Proposal, (C) initiate, solicit or
encourage, or take any action to facilitate the making of any Acquisition
Proposal or (D) enter into any agreement or understanding in respect of any
Acquisition Proposal.



         Without prejudice to the rights and remedies otherwise available to
each of the parties hereto, each such party shall be entitled to equitable
relief by way of specific performance, injunction or otherwise if the other
party or any of its Representatives breach or threaten to breach any of the
provisions of this letter agreement.

         It is further understood and agreed that no failure or delay by either
party in exercising any right, power or privilege hereunder shall operate as a
waiver thereof, nor shall any single or partial exercise thereof preclude any
other or further exercise thereof or the exercise of any right, power or
privilege hereunder.

         This letter agreement shall be deemed a contract made under, and for
all purposes shall be construed in accordance with, the laws of the Commonwealth
of Massachusetts, without reference to its conflicts of laws principles.

         This letter agreement shall not be assigned by either party, by
operation of law or otherwise, without the prior written consent of the other
party.

         This letter agreement contains the entire agreement between Abbott and
the Company concerning confidentiality of Proprietary Information, and no
modification of this letter agreement or waiver of the terms and conditions
hereof shall be binding upon Abbott or the Company, unless approved in writing
by each of the parties hereto.

<PAGE>

                                          6

         Please confirm your agreement with the foregoing by signing and
returning to the undersigned the duplicate copy of this letter enclosed
herewith.

                                        MEDISENSE, INC.


                                        By
                                           ----------------------------
                                           Name:
                                           Title:

Accepted and Agreed
as of the date
first written above.

ABBOTT LABORATORIES


By
  ----------------------------
  Name:
  Title:



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