
<PAGE>

                                                                       EXHIBIT C

                            DIAMETRICS MEDICAL, INC.

                             STOCK PURCHASE WARRANT

THE WARRANTS EVIDENCED HEREBY AND THE SHARES OF STOCK ISSUABLE UPON EXERCISE
THEREOF HAVE NOT BEEN REGISTERED UNDER SECURITIES ACT OF 1933, AS AMENDED, AND
MAY NOT BE OFFERED OR SOLD WITHOUT REGISTRATION UNLESS AN EXEMPTION FROM
REGISTRATION IS AVAILABLE UNDER SUCH ACT OR THE RULES OR REGULATIONS PROMULGATED
THEREUNDER.

                                                                   June 28, 1999

                                     WARRANT

     To Subscribe for and Purchase Common Stock of Diametrics Medical, Inc.

      VOID AFTER 5:00 P.M., MINNEAPOLIS, MINNESOTA TIME, ON AUGUST 4, 2003,
  OR IF NOT A BUSINESS DAY, AS DEFINED HEREIN, AT 5:00 P.M., MINNEAPOLIS TIME,
                    ON THE IMMEDIATELY PRECEDING BUSINESS DAY

This certifies that, for valuable consideration, receipt of which is hereby
acknowledged, Hewlett-Packard Company, and permitted successors and assigns
("Holder") is entitled to purchase from Diametrics Medical, Inc. a Minnesota
corporation (the "Company") up to and including 452,381 fully paid and
nonassessable shares (the "Number of Shares") of the common stock of the
Company, $.01 par value (the "Common Stock"), on the terms set forth herein at
an exercise price per share equal to $8.40 (the "Purchase Price"). The Number of
Shares and the Purchase Price may be adjusted from time to time as described in
this Warrant.

      1. EXERCISE.

            1.1 TIME FOR EXERCISE. This Warrant may be exercised in whole or in
part at any time, and from time to time, during the period commencing on the
date of this Warrant and expiring on August 4, 2003.

            1.2 MANNER OF EXERCISE. This Warrant shall be exercised by
delivering it to the Company with the exercise form duly completed and signed,
specifying the number of shares as to which the Warrant is being exercised at
that time (the "Exercise Number"). The Holder shall simultaneously deliver to
the Company cash or a certified check or wire transfer in an amount equal to the
Exercise Number multiplied by the Purchase Price, and the Holder shall be
entitled to receive the full Exercise Number of shares of Common Stock.

            1.3 EFFECTIVE DATE OF EXERCISE. Promptly (but in any case within ten
business days) after any exercise, the Company shall deliver to the Holder (a)
duly executed
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certificates in the name or names specified in the exercise notice representing
the aggregate number of shares issuable upon such exercise, and (b) if this
Warrant is exercised only in part, a new Warrant of like tenor exercisable for
the balance of the Number of Shares. Such certificates shall be deemed to have
been issued, and the person receiving them shall be deemed to be a holder of
record of such shares, as of the close of business on the date the actions
required in Section 1.2 shall have been completed or, if on that date the stock
transfer books of the Company are closed, as of the next business day.

      2. TRANSFER OF WARRANTS AND STOCK.

            2.1 TRANSFER RESTRICTIONS. This Warrant shall be freely transferable
by the Holder in accordance with the terms hereof; provided, however, that
neither this Warrant nor the securities issuable upon its exercise may be sold,
transferred or pledged unless the Company shall have been supplied with
reasonably satisfactory evidence that such transfer is not in violation of the
Securities Act of 1933, as amended (the "Securities Act"), and any applicable
state securities laws. The Company may place a legend to that effect on this
Warrant, any replacement Warrant and each certificate representing shares
issuable upon exercise of this Warrant. Subject to the satisfaction of this
condition only, this Warrant shall be freely transferable by the Holder.

            2.2 MANNER OF TRANSFER. Upon delivery of this Warrant to the Company
with the assignment form duly completed and signed, the Company will promptly
(but in any case within five (5) business days) execute and deliver to each
transferee and, if applicable, the Holder, Warrants of like tenor evidencing the
rights (a) of the transferee(s) to purchase the Number of Shares specified for
each in the assignment forms, and (b) of the Holder to purchase any
untransferred portion, which in the aggregate shall equal the number of Shares
of the original Warrant. If this Warrant is properly assigned in compliance with
Section 2, it may be exercised by an assignee without having a new Warrant
issued.

            2.3 LOSS, DESTRUCTION OF WARRANT CERTIFICATES. Upon receipt of (a)
evidence reasonably satisfactory to the Company of the loss, theft, destruction
or mutilation of any Warrant and (b) except in the case of mutilation, an
indemnity or security reasonably satisfactory to the Company, the Company will
promptly (but in any case within five (5) business days) execute and deliver a
replacement Warrant of like tenor representing the right to purchase the same
Number of Shares.

      3. COST OF ISSUANCES. The Company shall pay all expenses, transfer taxes
and other charges payable in connection with the preparation, issuance and
delivery of stock certificates or replacement Warrants, except for any transfer
tax or other charge imposed as a result of (a) any issuance of certificates in
any name other than the name of the Holder, or (b) any transfer of the Warrant.
The Company shall not be required to issue or deliver any Stock certificate or
Warrant until it receives reasonably satisfactory evidence that any such tax or
other charge has been paid by the Holder.


                                      -2-
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      4. ANTI-DILUTION PROVISIONS. If any of the following events occur at any
time hereafter during the life of this Warrant, then the Purchase Price and the
Number of Shares immediately prior to such event shall be changed as described
in order to prevent dilution:

            4.1 DIVIDENDS; STOCK SPLITS ETC. In case the Company shall (a) pay a
dividend in shares of Common Stock or make a distribution in shares of Common
Stock, (b) subdivide or reclassify its outstanding shares of Common Stock into a
greater number of shares, or (c) combine or reclassify its outstanding shares of
Common Stock into a smaller number of shares, the Number of Shares purchasable
upon the exercise of this Warrant immediately prior thereto shall be adjusted so
that the Number of Shares purchasable upon exercise of this Warrant shall be
determined by multiplying the Number of Shares theretofore purchasable upon the
exercise of this Warrant by a fraction, of which the numerator shall be the
number of shares of Common Stock outstanding immediately following such action
and of which the denominator shall be the number of shares of Common Stock
outstanding immediately prior thereto. Such adjustment shall be made whenever
any event listed above shall occur and shall become effective immediately after
the record date in the case of a dividend and shall become effective immediately
after the effective date in the case of a subdivision, combination or
reclassification. If the Company declares a dividend in money on its Common
Stock and at substantially the same time offers its Stockholders a right to
purchase new shares of Common Stock or of capital stock of any other class from
the proceeds of such dividend, or for an amount substantially equal to such
dividend, all shares of Common Stock or of capital stock of any other class so
issued shall for purposes hereof be deemed issued as a Stock dividend.

            4.2 ISSUANCE OF RIGHTS OR WARRANTS TO HOLDERS. In case the Company
shall issue rights, options or warrants to all holders of its shares of Common
Stock entitling them (for a period expiring within 45 days after the record date
therefor) to subscribe for or purchase shares of Common Stock at a price per
share which is lower at the record date mentioned below than the then Current
Market Price per share of Common Stock (as hereinafter defined), the Number of
Shares thereafter purchasable upon the exercise of this Warrant shall be
determined by multiplying the Number of Shares theretofore purchasable upon
exercise of this Warrant by a fraction, of which the numerator shall be the
number of shares of Common Stock outstanding on such record date plus the number
of additional shares of Common Stock offered for subscription or purchase, and
of which the denominator shall be the number of shares of Common Stock
outstanding on such record date plus the number of shares which the aggregate
offering price of the total number shares of Common Stock so offered would
purchase at the then Current Market Price per share of Common Stock. For
purposes of this Section 4.2, the issuance of rights, options or warrants to
subscribe for or purchase securities convertible into Common Stock shall be
deemed to be the issuance of rights, options or warrants to purchase the Common
Stock into which such securities are convertible at an aggregate offering price
equal to the aggregate offering price of such securities plus the minimum
aggregate amount (if any) payable upon conversion of such securities into Common
Stock.

            4.3 MERGER; CONSOLIDATION; SALE OF ASSETS. In case of (a) the
consolidation or the merger of the Company, (b) the sale of all or substantially
all of the properties


                                      -3-
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and assets of the Company to any Person, (c) any capital reorganization by the
Company, or (d) any voluntary or involuntary dissolution, liquidation, or
winding up of the Company, this Warrant shall, after any such event, entitle the
Holder to receive upon exercise the number of shares of Stock or other
securities or property (including cash) of the Person (if applicable) resulting
from such event, which the holder of securities deliverable upon exercise of
this Warrant (at the time of such event) would have been entitled to receive
upon such event; and in any such case the provisions of Section 4 with respect
to the rights and interests thereafter of the holders of this Warrant shall be
appropriately adjusted so as to be applicable, as nearly as practicable, to any
shares of Stock or other securities or any property (including cash) thereafter
deliverable upon exercise of this Warrant. The Person resulting from such sale
or consolidation or surviving such merger or to which such sale shall be made
shall execute and deliver to the Holder a supplemental agreement as provided in
Section 6.5 below. Any adjustment pursuant to this Section 4.3 which shall be
approved in good faith by the Board of Directors of the Company pursuant to a
resolution delivered to the Holder shall be conclusive for all purposes hereof.
For the purposes of this Agreement "person" means any individual, partnership,
firm, corporation, limited liability company or partnership, association, trust,
unincorporated organization or other entity, as well as any syndicate or group
that would be deemed to be a person under Section 13(d)(3) of the Securities
Exchange Act of 1934, as amended.

            4.4 OTHER DISTRIBUTIONS. In case the Company shall distribute to all
holders of its shares of Common Stock shares of Stock other than Common Stock or
evidences of its indebtedness or assets (excluding cash dividends or
distributions payable out of consolidated earnings or retained earnings and
dividends or distributions referred to in Section 4.1 above) or rights, options,
warrants or convertible or exchangeable securities containing the right to
subscribe for or purchase shares of Common Stock (excluding those referred to in
Section 4.2 above), then in each case the Number of Shares thereafter
purchasable upon the exercise of this Warrant shall be determined by multiplying
the Number of Shares theretofore purchasable upon the exercise of this Warrant,
by a fraction of which the numerator shall be the Current Market Price per share
of Common Stock on the record date mentioned below in this Section 4.4 plus the
then fair value (as reasonably determined by the Board of Directors of the
Company in good faith, whose determination shall be conclusive absent manifest
error, irrespective of the accounting treatment thereof) of the portion of the
shares of Stock other than Common Stock or assets or evidences of indebtedness
so distributed or of such subscription rights, options or warrants, or of such
convertible or exchangeable securities applicable to one share of Common Stock,
and of which the denominator shall be the Current Market Price per share of
Common Stock on such record date. Such adjustment shall be made whenever any
such distribution is made, and shall become effective immediately after the
record date for the determination of Stockholders entitled to receive such
distribution.

            4.5 ADDITIONAL ADJUSTMENT OF PURCHASE PRICE. Whenever the Number of
Shares purchasable upon the exercise of this Warrant is adjusted, as provided
herein, the Purchase Price payable upon exercise of this Warrant shall be
adjusted by multiplying such Purchase Price immediately prior to such adjustment
by a fraction, of which the numerator shall be the Number of Shares purchasable
upon the exercise of this Warrant immediately prior to such adjustment, and of
which the denominator shall be the Number of Shares so purchasable immediately
thereafter.


                                      -4-
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            4.6 NO DE MINIMIS ADJUSTMENTS. No adjustment in the Purchase Price
shall be required unless such adjustment would require an increase or decrease
of at least 1% in such price; provided, however, that any adjustments which by
reason of this Section 4.6 are not required to be made shall be carried forward
and taken into account in any subsequent adjustment. All calculations under this
Section 4.6 shall be made to the nearest one-twentieth of a cent or to the
nearest one-hundredth of a share, as the case may be.

            4.7 TREASURY SHARES. For the purpose of Section 4, shares of Common
Stock or other securities held in the treasury of the Company shall not be
deemed to be outstanding, and the sale or other deposition of any shares of
Common Stock or other securities held in the treasury of the Company shall be
deemed an issuance thereof.

            4.8 CORPORATE ACTION. Before taking any action which would cause an
adjustment reducing the Purchase Price below the then par value, if any, of the
shares of Common Stock issuable upon exercise of this Warrant, the Company shall
take any corporate action which may, in the opinion of its counsel, be necessary
in order that the Company may validly and legally issue fully paid and
nonassessable shares of Common Stock at such adjusted Purchase Price.

            4.9 INDEPENDENT PUBLIC ACCOUNTANTS. The certificate of a "Big Five"
firm of independent public accountants selected by the Board of Directors of the
Company shall be conclusive evidence of the correctness of any computation made
under Section 4.

            4.10 NOTICE OF CERTAIN EVENTS. In case at any time prior to the
expiration date of this Warrant:

                  (i) the Company shall declare a dividend (or any other
distribution) on the Common Stock (other than a dividend in cash out of retained
earnings); or

                  (ii) the Company shall authorize the granting to the holders
of Common Stock of rights or warrants to subscribe for or purchase any shares of
stock of any class or of any other rights; or

                  (iii) there shall be any reclassification of the Common Stock
of the Company (other than a subdivision or combination of its outstanding
Common Stock); or

                  (iv) there shall be any capital reorganization by the Company;
or

                  (v) there shall be a consolidation or merger involving the
Company or sale of all or substantially all of the Company's property and assets
(except a merger or other reorganization in which the Company shall be the
surviving corporation or a consolidation, merger or sale with a wholly-owned
subsidiary); or

                  (vi) there shall be voluntary or involuntary dissolution,
liquidation and winding up by the Company or dividend or distribution to holders
of Common Stock (other than the customary cash and stock dividends); or


                                      -5-
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                  (vii) any other action shall occur which would give rise to an
adjustment to the Purchase Price or the Number of Shares hereunder, then in any
one or more of said cases, the Company shall cause to be delivered to the
Holder, at the earliest practicable time (and, in any event, not less than 25
days before any record date or other date set for definitive action), notice of
the date on which the books of the Company shall close or a record shall be
taken for such dividend, distribution or subscription rights or such
reorganization, sale, consolidation, merger, dissolution, liquidation or winding
up shall take place, as the case may be. Such notice shall also set forth such
facts as shall indicate the effect of such action (to the extent such effect may
be known at the date of such notice) on the Purchase Price and the kind and
amount of the shares of stock and other securities and property deliverable upon
exercise of this Warrant. Such notice shall also specify the date, if known, as
of which the holders of record of the Common Stock shall participate in said
dividend, distribution or subscription rights or shall be entitled to exchange
their shares of the Common Stock for securities or other property (including
cash) deliverable upon such reorganization, sale, consolidation, merger,
dissolution, liquidation or winding up, as the case may be (on which date, in
the event of voluntary or involuntary dissolution, liquidation, or winding up of
the Company, other than dissolution, liquidation or winding up following a
consolidation or merger of the Company with or into, or sale of substantially
all of its assets to, another corporation, the rights to exercise this Warrant
shall terminate).

            4.11 OTHER SECURITIES ADJUSTMENTS. If as a result of Section 4, a
Holder is entitled to receive any securities other than Common Stock upon
exercise of this Warrant, the number and purchase price of such securities shall
thereafter be adjusted from time to time in the same manner as provided pursuant
to Section 4 for Common Stock. The allocation of purchase price between various
securities shall be made in writing by the Board of Directors of the Company in
good faith at the time of the event by which the holder became entitled to
receive new securities, and a copy sent to the Holder.

            4.12 NOTICES OF ADJUSTMENTS. When any adjustment is required to be
made under Section 4, the Company shall promptly (a) determine such adjustments,
(b) prepare and retain on file a statement describing in reasonable detail the
method used in arriving at the adjustment; and (c) cause a copy of such
statement, together with any agreement required by Section 6.5, to be mailed to
the Holder within 10 days after the date on which the circumstances giving rise
to such adjustment occurred.

            4.13 COMPUTATIONS AND ADJUSTMENTS. Upon each computation of an
adjustment under this Section 4, the Purchase Price shall be computed to the
nearest cent and the Number of Shares shall be calculated to the next highest
whole share. However, the fractional amount shall be used in calculating any
future adjustments. No fractional shares of Common Stock shall be issued in
connection with the exercise of this Warrant, but the Company shall, in the case
of the final exercise under this Warrant, make a cash payment for any fractional
shares based on the Current Market Price of the Common Stock on the date of
exercise. Notwithstanding any changes in the Purchase Price or the Number of
Shares, this Warrant, and any Warrants issued in replacement or upon transfer
thereof, may continue to state the initial Purchase Price and the Number of
Shares. Alternatively, the Company may elect to issue a new Warrant or Warrants
of like tenor for the


                                      -6-
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additional shares of Common Stock purchasable hereunder or, upon surrender of
the existing Warrant, to issue a replacement Warrant evidencing all the Warrants
to which the Holder is entitled after such adjustments.

            4.14 EXERCISE BEFORE PAYMENT DATE. In the event that this Warrant is
exercised after the record date for any event requiring an adjustment, but prior
to the actual event, the Company may elect to defer payment of the adjusted
amount to the Holder until the actual event occurs; provided, however, that the
Company shall deliver a due bill or other appropriate instrument to the Holder
transferable to the same extent as the other securities issuable on exercise
evidencing the Holder's right to receive such additional amount upon the
occurrence of the event requiring such adjustment.

            4.15 CURRENT MARKET PRICE. "Current Market Price" for the Common
Stock on any given date means (a) the closing price on the previous trading day
for the Common Stock on the principal stock exchange on which the Common Stock
is traded (or, in the case of issuances of stock options with an exercise price
equal to fair market value on the date of grant pursuant to the terms of a plan,
such date) or (b) if not so traded, the closing price (or, if no closing price
is available, the average of the bid and asked prices) for such date on the
NASDAQ if the Common Stock is listed on the NASDAQ or (c) if not listed on any
exchange or quoted on the NASDAQ, such value as may be determined in good faith
by the Company's Board of Directors, which determination shall be conclusively
binding on the parties.

      5. REDEMPTION.

            5.1 REDEMPTION AT COMPANY'S OPTION. The Company may, upon 30 days
prior written notice (the "Redemption Notice") to the Holder, redeem all, but
not less than all of the Warrants granted hereunder that have not been exercised
before the date referred to in Section 5.2(d) at a redemption price of $0.05 per
Warrant (the "Redemption Price"), so long as the Current Market Price (as
defined in Section 4.15(a) and (b) above) is greater than the following prices
(the "Target Prices") for any period of 20 consecutive trading days preceding
the date the Redemption Notice is given:

           Time Period                             Target Price
- -----------------------------------     -----------------------------------

  August 4, 1999--August 4, 2000                      $12.10

  August 5, 2000--August 4, 2001                      $14.52

  August 5, 2001--August 4, 2002                      $17.42

  August 5, 2002--August 4, 2003                      $20.90

      The date fixed for redemption of this Warrant is referred to herein as the
"Redemption Date."


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            5.2 REDEMPTION NOTICE. The Redemption Notice shall specify (a) the
Redemption Price, (b) the Redemption Date, (c) the place where this Warrant
shall be delivered and the Redemption Price paid, and (d) that the right to
exercise the Warrant shall terminate at 5:00 p.m. (Minneapolis time) on the
business day immediately preceding the Redemption Date. No failure to mail such
notice nor any defect therein or in the mailing thereof shall affect the
validity of the proceedings for such redemption except as to a Holder (i) to
whom notice was not mailed (ii) whose notice was defective.

            5.3 FAILURE TO EXERCISE. Any right to exercise this Warrant shall
terminate at 5:00 p.m. (Minneapolis time) on the business day immediately
preceding the Redemption Date. On and after the Redemption Date, the Holder
shall have no further rights except to receive, upon surrender of this Warrant,
the Redemption Price.

            5.4 SURRENDER OF WARRANT. From and after the Redemption Date, the
Company shall, at the place specified in the Redemption Notice, upon
presentation and surrender to the Company by or on behalf of the Holder of the
Warrant to be redeemed, deliver or cause to be delivered to or upon the written
order of the Holder a sum in cash equal to the Redemption Price of this Warrant.
From and after the Redemption Date and upon the deposit or setting aside by the
Company of a sum sufficient to redeem this Warrant, it shall expire and become
void and all rights hereunder, except the right to receive payment of the
Redemption Price, shall cease.

            5.5 ADJUSTMENTS. If the shares of Common Stock are subdivided or
combined into a greater or smaller number of shares of Common Stock, the Target
Prices shall be proportionally adjusted by the ratio which the total number of
shares of Common Stock outstanding immediately prior to such event bears to the
total number of shares of Common Stock to be outstanding immediately after such
event.

      6. COVENANTS. The Company agrees that:

            6.1 RESERVATION OF STOCK. During the period in which this Warrant
may be exercised, the Company will reserve sufficient authorized but unissued
securities to enable it to satisfy its obligations on exercise of this Warrant
and shall use its reasonable best efforts to cause all shares of Common Stock
issued upon the exercise of this Warrant to be listed on any exchanges on which
the Common Stock is then listed. If at any time the Company's authorized
securities shall not be sufficient to allow the exercise of this Warrant, the
Company shall take such corporate action as may be necessary to increase its
authorized but unissued securities to be sufficient for such purpose;

            6.2 NO LIENS, ETC. All securities that may be issued upon exercise
of this Warrant will, upon issuance, be validly issued, fully paid,
nonassessable and free from all taxes, liens and charges with respect to the
issue thereof, and shall be listed on any exchanges on which that class of
securities is listed;

            6.3 FURNISH INFORMATION. During the term of this Warrant, the
Company will promptly deliver to the Holder copies of all financial statements,
reports and proxy statements which the Company shall have sent to its
stockholders generally;


                                      -8-
<PAGE>

            6.4 STOCK AND WARRANT TRANSFER BOOKS. Except upon dissolution,
liquidation or winding up or for ordinary holidays and weekends, the Company
will not at any time close its stock or warrant transfer books so as to result
in preventing or delaying the exercise or transfer of this Warrant; and

            6.5 MERGER; CONSOLIDATION OR SALE OF ASSETS OF THE COMPANY. Except
in the case of a merger or consolidation where the consideration is payable
entirely in cash or obligations, the Company will not merge or consolidate with
or into any Person, or sell or otherwise transfer its property, assets and
business substantially as an entirety to a successor Person, unless the Person
resulting from such merger or consolidation (if not the Company), or such
successor Person, shall expressly assume, by supplemental agreement reasonably
satisfactory in form to the then Majority Holders (as defined below) and
executed and delivered to the Holder, the due and punctual performance and
observance of each and every covenant and condition of this Agreement to be
performed and observed by the Company. "Majority Holders", as of any date, shall
mean the holders of this Warrant (or replacement warrants issued pursuant
hereto) and of the substantially similar warrants issued contemporaneously
herewith pursuant to the Common Stock Purchase Agreement (or replacement
warrants issued pursuant thereto) who together have rights to exercise such
warrants for a majority of the Warrant Shares (as defined in the Common Stock
Purchase Agreement).

      7. STATUS OF HOLDER.

            7.1 NOT A STOCKHOLDER. Unless the Holder exercises this Warrant in
writing, the Holder shall not be entitled to any rights (a) as a stockholder of
the Company with respect to the shares as to which the Warrant is exercisable
including, without limitation, the right to vote or receive dividends or other
distributions, or (b) to receive any notice of any proceedings of the Company
except as otherwise provided in this Warrant.

            7.2 LIMITATION OF LIABILITY. Unless the Holder exercises this
Warrant in writing, the Holder's rights and privileges hereunder shall not give
rise to any liability for the Purchase Price or as a stockholder of the Company,
whether to the Company or its creditors.

      8. REGISTRATION RIGHTS. The shares purchasable upon exercisable of this
Warrant shall be Registerable Securities as defined in Section 10.1 of the
Common Stock Purchase Agreement.

      9. GENERAL PROVISIONS.

            9.1 COMPLETE AGREEMENT; Modifications. This Warrant and any
documents referred to herein or executed contemporaneously herewith constitute
the parties' entire agreement with respect to the subject matter hereof and
supersede all agreements, representations, warranties, statements, promises and
understandings, whether oral or written, with respect to the subject matter
hereof. The Warrant may not be amended, altered or modified except by a writing
signed by the parties.


                                      -9-
<PAGE>

            9.2 COOPERATION. Each party hereto agrees to execute any and all
further documents and writings and to perform such other reasonable actions
which may be or become necessary or expedient to effectuate and carry out this
Warrant.

            9.3 NOTICES. All notices under this Warrant shall be in writing and
shall be delivered by personal service or telecopy or certified mail return
receipt requested (if such service is not available, then by first class mail),
postage prepaid, to such address as may be designated from time to time by the
relevant party, and which shall initially be:

                  (a) IF TO THE COMPANY:

                      Diametrics Medical, Inc.
                      2658 Patton Road
                      Roseville, Minnesota 55113
                      Attention: Chief Financial Officer
                      Telecopy: (612) 639-8459

                      WITH A COPY TO:

                      Dorsey & Whitney LLP
                      Pillsbury Center South
                      220 South Sixth Street
                      Minneapolis, Minnesota 55402
                      Attention: Kenneth Cutler
                      Telecopy: (612) 340-8738

                  (b) IF TO THE HOLDER:

                      Hewlett-Packard Company
                      3000 Hanover Street, Mail Stop 20BT
                      Palo Alto, California 94304
                      Attention: Director, Corporate Development
                      Phone: (650) 857-1501
                      Fax: (650) 852-8342

                      WITH A COPY TO:

                      Hewlett-Packard Company
                      3000 Hanover Street, Mail Stop BQ
                      Palo Alto, California 94304
                      Attention: General Counsel
                      Phone: (650) 857-1501
                      Fax: (650) 857-4392


                                      -10-
<PAGE>

Any notice sent by certified mail shall be deemed to have been given three days
after the date on which it is mailed. All other notices shall be deemed given
when received. No objection may be made to the manner of delivery of any notice
actually received in writing by an authorized agent of a party.

            9.4 NO THIRD-PARTY BENEFITS; SUCCESSORS AND ASSIGNS. None of the
provisions of this Warrant shall be for the benefit of, or enforceable by, any
third-party beneficiary. Except as provided herein to the contrary, this Warrant
shall be binding upon and inure to the benefit of the parties, their respective
successors and permitted assigns.

            9.5 GOVERNING LAW. This Warrant concerns a Minnesota corporation,
and all questions with respect to the Warrant and the rights and liabilities of
the parties will be governed by the laws of Minnesota regardless of the choice
of law provisions of Minnesota or any other jurisdiction.

            9.6 WAIVERS STRICTLY CONSTRUED. With regard to any power, remedy or
right provided herein or otherwise available to any party hereunder (a) no
waiver or extension of time shall be effective unless expressly contained in a
writing signed by the waiving party; and (b) no alteration, modification or
impairment shall be implied by reason of any previous waiver, extension of time,
delay or omission in exercise, or other indulgence.

            9.7 SEVERABILITY. The validity, legality or enforceability of the
remainder of this Warrant shall not be affected even if one or more of its
provisions shall be held to be invalid, illegal or unenforceable in any respect.

            9.8 ATTORNEYS' FEES. Should any litigation or arbitration be
commenced (including any proceedings in a bankruptcy court) between the parties
hereto or their representatives concerning any provisions of this Warrant or the
rights and duties of any person or entity hereunder the party or parties
prevailing in such proceeding shall be entitled, in addition to such other
relief as may be granted, to the attorneys' fees and court costs incurred by
reason of such litigation.

      IN WITNESS WHEREOF, the Company has caused this Warrant to be duly
executed effective as of June 28, 1999.

                                        DIAMETRICS MEDICAL, INC.



                                        By: /s/ Laurence L. Betterley
                                            ------------------------------------
                                        Title: Senior Vice President and Chief
                                        Financial Officer


                                     -11-
<PAGE>

                                 ASSIGNMENT FORM

      FOR VALUE RECEIVED, __________________________________ hereby sells,
assigns and transfers to the transferee named below the rights to purchase
______________ of the Number of Shares under this Warrant, together with all
rights, title and interest therein. The rights to purchase the remaining Number
of Shares shall remain the property of the undersigned.

Dated: ____________________________

                                        [NAME OF HOLDER]

                                        By       _______________________________

                                        Name     _______________________________
                                                         (Please Print)

                                        Address: _______________________________

                                                 _______________________________

                                                 _______________________________

Employer Identification Number,
Social Security Number or other
identifying number:

_______________________________


                                      -12-
<PAGE>

                                 EXERCISE FORM

                     To Be Executed Upon Exercise Of Warrant

      The undersigned hereby exercises the Warrant with regard to ___________
shares of Common Stock and herewith makes payment of the purchase price in full.
The undersigned requests that certificate(s) for such shares and the Warrant for
any unexercised portion of this Warrant be issued to the Holder.

Dated: ____________________________

                                        [NAME OF HOLDER]

                                        By       _______________________________

                                        Name     _______________________________
                                                         (Please Print)

                                        Address: _______________________________

                                                 _______________________________

                                                 _______________________________

Employer Identification Number,
Social Security Number or other
identifying number:

___________________________________


                                      -13-
