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                                                                    EXHIBIT 10.5


                            DIAMETRICS MEDICAL, INC.
                              AMENDED AND RESTATED
                             1990 STOCK OPTION PLAN

1.      Purpose of Plan.

                  This Plan shall be known as the "DIAMETRICS MEDICAL, INC. 1990
STOCK OPTION PLAN" and is hereinafter referred to as the "Plan." The purpose of
the Plan is to aid in maintaining and developing personnel capable of assuring
the future success of Diametrics Medical, Inc., a Minnesota corporation (the
"Company"), to offer such personnel additional incentives to put forth maximum
efforts for the success of the business, and to afford them an opportunity to
acquire a proprietary interest in the Company through stock options and other
long-term incentive awards as provided herein. Options granted under this Plan
may be either incentive stock options ("Incentive Stock Options") within the
meaning of Section 422 of the Internal Revenue Code of 1986 (the "Code"), or
options which do not qualify as Incentive Stock Options. Awards granted under
this Plan shall be SARs, restricted stock or performance awards as hereinafter
described.

2.       Stock Subject to Plan.

                  Subject to the provisions of Section 15 hereof, the stock to
be subject to options or other awards under the Plan shall be the Company's
authorized but unissued shares of Common Stock, par value $.01 per share. Such
shares may be either authorized but unissued shares, or issued shares which have
been reacquired by the Company. Subject to adjustment as provided in Section 15
hereof, the maximum number of shares on which options may be exercised or other
awards issued under this Plan shall be 3,750,000 shares. If an option or award
under the Plan expires, or for any reason is terminated or unexercised with
respect to any shares, such shares shall again be available for options or
awards thereafter granted during the term of the Plan.

3.       Administration of Plan.

                  (a) The Plan shall be administered by a committee (the
"Committee") of two or more members of the Board of Directors of the Company,
none of whom shall be officers or employees of the Company and all of whom shall
be "disinterested persons" with respect to the Plan within the meaning of Rule
16b-3 under the Securities Exchange Act of 1934, as amended (the "Exchange
Act"), or any successor rule or regulation thereto. The members of any such
committee shall be appointed by and serve at the pleasure of the Board of
Directors.

                  (b) The Committee shall have plenary authority in its
discretion, but subject to the express provisions of the Plan: (i) to determine
the purchase price of the
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Common Stock covered by each option or award, (ii) to determine the employees to
whom and the time or times at which such options and awards shall be granted and
the number of shares to be subject to each, (iii) to determine the form of
payment to be made upon the exercise of an SAR or in connection with performance
awards, either cash, Common Stock of the Company or a combination thereof, (iv)
to determine the terms of exercise of each option and award, (v) to accelerate
the time at which all or any part of an option or award may be exercised, (vi)
to amend or modify the terms of any option or award with the consent of the
optionee, (vii) to interpret the Plan, (viii) to prescribe, amend and rescind
rules and regulations relating to the Plan, (ix) to determine the terms and
provisions of each option and award agreement under the Plan (which agreements
need not be identical), including the designation of those options intended to
be Incentive Stock Options, and (x) to make all other determinations necessary
or advisable for the administration of the Plan, subject to the exclusive
authority of the Board of Directors under Section 16 herein to amend or
terminate the Plan.

                  (c) The Committee shall select one of its members as its
Chairman and shall hold its meetings at such times and places as it may
determine. A majority of its members shall constitute a quorum, provided that if
the Committee is comprised of no more than two members, all of its members must
be present to constitute a quorum. All determinations of the Committee shall be
made by not less than a majority of its members, provided that if the Committee
is comprised of no more than two members, such determinations may not be made by
less than all of its members. Any decision or determination reduced to writing
and signed by all of the members of the Committee shall be fully effective as if
it had been made by a majority vote at a meeting duly called and held. The grant
of an option or award shall be effective only if a written agreement shall have
been duly executed and delivered by and on behalf of the Company following such
grant. The Committee may appoint a Secretary and may make such rules and
regulations for the conduct of business as it shall deem advisable.

                  (d) The Chief Executive Officer of the Company shall have the
authority, as granted by the Committee pursuant to clause (ix) of subsection (b)
of this Section 3, to grant, pursuant to the Plan, options or other awards to
eligible persons who are not considered by the Company as its officers or
directors for purposes of Section 16 of the Securities Exchange Act of 1934, as
amended. The Chief Executive Officer of the Company shall provide information as
to any grants made pursuant to this subsection to the Committee at their next
meeting.



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4.       Eligibility.

                  Incentive Stock Options may only be granted under this Plan to
any full or part-time employee (which term as used herein includes, but is not
limited to, officers and directors who are also employees) of the Company and of
its present and future subsidiary corporations within the meaning of Section
424(f) of the Code (herein called "subsidiaries"). Full or part-time employees,
consultants or independent contractors to the Company or one of its subsidiaries
shall be eligible to receive options which do not qualify as Incentive Stock
Options and awards. In determining the persons to whom options and awards shall
be granted and the number of shares subject to each, the Committee may take into
account the nature of services rendered by the respective employees or
consultant their present and potential contributions to the success of the
Company and such other factors as the Committee in its discretion shall deem
relevant. A person who has been granted an option or award under this Plan may
be granted additional options or awards under the Plan if the Committee shall so
determine; provided, however, that for Incentive Stock Options granted after
December 31, 1986, to the extent the aggregate fair market value (determined at
the time the Incentive Stock Option is granted) of the Common Stock with respect
to which all Incentive Stock Options are exercisable for the first time by an
employee during any calendar year (under all plans described in subsection (d)
of Section 422 of the Code of his employer corporation and its parent and
subsidiary corporations) exceeds $100,000, such options shall be treated as
options which do not qualify as Incentive Stock Options. Nothing in the Plan or
in any agreement thereunder shall confer on any employee any right to continue
in the employ of the Company or any of its subsidiaries or affect, in any way,
the right of the Company or any of its subsidiaries to terminate his or her
employment at any time.

5.       Price.

                  The option price for all Incentive Stock Options granted under
the Plan shall be determined by the Committee but shall not be less than 100% of
the fair market value of the Common Stock at the date of grant of such option.
The option price for options granted under the Plan which do not qualify as
Incentive Stock Options and, if applicable, the price for all awards shall also
be determined by the Committee. For purposes of the preceding sentence and for
all other valuation purposes under the Plan, the fair market value of shares of
Common Stock shall be (i) the closing price of the Common Stock as reported for
composite transactions if the Common Stock is then traded on a national
securities exchange, (ii) the last sale price if the Common Stock is then quoted
on the NASDAQ National Market System, or (iii) the average of the closing
representative bid and asked prices of the Common Stock as reported on NASDAQ on
the date as of which the fair market value is being determined. If on the date
of grant of any option or award hereunder the Common Stock is not traded on an
established

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securities market, the Committee shall make a good faith attempt to satisfy the
requirements of this Section 5 and in connection therewith shall take such
action as it deems necessary or advisable.

6.       Term.

                  Each option and award and all rights and obligations
thereunder shall expire on the date determined by the Committee and specified in
the option or award agreement. The Committee shall be under no duty to provide
terms of like duration for options or awards granted under the Plan, but the
term of an Incentive Stock Option may not extend more than ten (10) years from
the date of grant of such option and the term of options granted under the Plan
which do not qualify as Incentive Stock Options may not extend more than fifteen
(15) years from the date of granting of such option.

7.       Exercise of Option or Award.

                  (a) The Committee shall have full and complete authority to
determine whether an option or award will be exercisable in full at any time or
from time to time during the term thereof, or to provide for the exercise
thereof in such installments, upon the occurrence of such events (such as
termination of employment for any reason) and at such times during the term of
the option as the Committee may determine and specify in the option or award
agreement.

                  (b) The exercise of any option or award granted hereunder
shall only be effective at such time that the sale of Common Stock pursuant to
such exercise will not violate any state or federal securities or other laws.
Only to the extent required in order to comply with Rule 16b-3 under the
Exchange Act, in the case of an option or other award granted to a person
considered by the Company as one of its officers or directors for purposes of
Section 16 of the Exchange Act, the terms of the option or other award will
require that such shares are not disposed of by such officer or director for a
period of at least six months from the date of grant.

                  (c) An optionee or grantee electing to exercise an option or
award shall give written notice to the Company of such election and of the
number of shares subject to such exercise. The full purchase price of such
shares shall be tendered with such notice of exercise. Payment shall he made to
the Company in cash (including bank check, certified check, personal check, or
money order), or, at the discretion of the Committee and as specified by the
Committee, (i) by delivering certificates for the Company's Common Stock already
owned by the optionee or grantee having a fair market value as of the date of
grant equal to the full purchase price of the shares, or (ii) by delivering the
optionee's or grantee's promissory note, which shall provide for interest at a
rate not less than the minimum rate required to avoid the imputation of

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income, original issue discount or a below-market-rate loan pursuant to Sections
483, 1274 or 7872 of the Code or any successor provisions thereto, or (iii) a
combination of cash, the optionee's or grantee promissory note and such shares.
The fair market value of such tendered shares shall be determined as provided in
Section 5 herein. The optionee's or grantee's promissory note shall be a full
recourse liability of the optionee and may, at the discretion of the Committee,
be secured by a pledge of the shares being purchased. Until such person has been
issued the shares subject to such exercise, he or she shall possess no rights as
a shareholder with respect to such shares.

8.       Stock Appreciation Rights.

                  (a) Grant. At the time of grant of an option or award under
the Plan (or at any other time), the Committee, in its discretion, may grant a
Stock Appreciation Right ("SAR") evidenced by an agreement in such form as the
Committee shall from time to time approve. Any such SAR may be subject to
restrictions on the exercise thereof as may be set forth in the agreement
representing such SAR, which agreement shall comply with and be subject to the
following terms and conditions and any additional terms and conditions
established by the Committee that are consistent with the terms of the Plan.

                  (b) Exercise. An SAR shall be exercised by the delivery to the
Company of a written notice which shall state that the holder thereof elects to
exercise his or her SAR as to the number of shares specified in the notice and
which shall further state what portion, if any, of the SAR exercise amount
(hereinafter defined) the holder thereof requests be paid to in cash and what
portion, if any, is to be paid in Common Stock of the Company. The Committee
promptly shall cause to be paid to such holder the SAR exercise amount either in
cash, in Common Stock of the Company, or any combination of cash and shares as
the Committee may determine. Such determination may be either in accordance with
the request made by the holder of the SAR or in the sole and absolute discretion
of the Committee. The SAR exercise amount is the excess of the fair market value
of one share of the Company's Common Stock on the date of exercise over the per
share exercise price in respect of which the SAR was granted, multiplied by the
number of shares as to which the SAR is exercised. For the purposes hereof, the
fair market value of the Company's shares of Common Stock shall be determined as
provided in Section 5 herein.

9.       Restricted Stock Awards.

                  Awards of Common Stock subject to forfeiture and transfer
restrictions may be granted by the Committee. Any restricted stock award shall
be evidenced by an agreement in such form as the Committee shall from time to
time approve, which agreement shall comply with and be subject to the following
terms and conditions and

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any additional terms and conditions established by the Committee that are
consistent with the terms of the Plan:

                  (a) Grant of Restricted Stock Awards. Each restricted stock
award made under the Plan shall be for such number of shares of Common Stock as
shall be determined by the Committee and set forth in the agreement containing
the terms of such restricted stock award. Such agreement shall set forth a
period of time during which the grantee must remain in the continuous employment
of the Company in order for the forfeiture and transfer restrictions to lapse.
If the Committee so determines, the restrictions may lapse during such
restricted period in installments with respect to specified portions of the
shares covered by the restricted stock award. The agreement may also, in the
discretion of the Committee, set forth performance or other conditions that will
subject the Common Stock to forfeiture and transfer restrictions. The Committee
may, at its discretion, waive all or any part of the restrictions applicable to
any or all outstanding restricted stock awards.

                  (b) Delivery of Common Stock and Restrictions. At the time of
a restricted stock award, a certificate representing the number of shares of
Common Stock awarded thereunder shall be registered in the name of the grantee.
Such certificate shall be held by the Company or any custodian appointed by the
Company for the account of the grantee subject to the terms and conditions of
the Plan, and shall bear such a legend setting forth the restrictions imposed
thereon as the Committee, in its discretion, may determine. The grantee shall
have all rights of a shareholder with respect to the Common Stock, including the
right to receive dividends and the right to vote such shares, subject to the
following restrictions: (i) the grantee shall not be entitled to delivery of the
stock certificate until the expiration of the restricted period and the
fulfillment of any other restrictive conditions set forth in the restricted
stock agreement with respect to such Common Stock; (ii) none of the shares of
Common Stock may be sold, assigned, transferred, pledged, hypothecated or
otherwise encumbered or disposed of during such restricted period or until after
the fulfillment of any such other restrictive conditions; and (iii) except as
otherwise determined by the Committee, all of the Common Stock shall be
forfeited and all rights of the grantee to such Common Stock shall terminate,
without further obligation on the part of the Company, unless the grantee
remains in the continuous employment of the Company for the entire restricted
period in relation to which such shares of Common Stock were granted and unless
any other restrictive conditions relating to the restricted stock award are met.
Any Common Stock, any other securities of the Company and any other property
(except for cash dividends) distributed with respect to the Common Stock subject
to restricted stock awards shall be subject to the same restrictions, terms and
conditions as such restricted Common Stock.


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                  (c) Termination of Restrictions. At the end of the restricted
period and provided that any other restrictive conditions of the restricted
stock award are met, or at such earlier time as otherwise determined by the
Committee, all restrictions set forth in the agreement relating to the
restricted stock award or in the Plan shall lapse as to the restricted Common
Stock subject thereto, and a stock certificate for the appropriate number of
shares of Common Stock, free of the restrictions and the restricted stock
legend, shall be delivered to the grantee or his beneficiary or estate, as the
case may be.

10.      Performance Awards.

                  The Committee is further authorized to grant performance
awards ("Performance Award"). Subject to the terms of this Plan and any
applicable award agreement, Performance Awards granted under the Plan (i) may be
denominated or payable in cash, Common Stock (including, without limitation,
restricted stock), other securities, other awards, or other property and (ii)
shall confer on the holder thereof rights valued as determined by the Committee,
in its discretion, and payable to, or exercisable by, the holder of the
Performance Awards, in whole or in part, upon the achievement of such
performance goals during such performance periods as the Committee, in its
discretion, shall establish. Subject to the terms of this Plan and any
applicable award agreement, the performance goals to be achieved during any
performance period, the length of any performance period, the amount of any
Performance Awards granted, and the amount of any payment or transfer to be made
by the grantee and by the Company under any Performance Awards shall be
determined by the Committee.

11.      Income Tax Withholding and Tax Bonuses.

                  (a) In order to comply with all applicable federal or state
income tax laws or regulations, the Company may take such action as it deems
appropriate to ensure that all applicable federal or state payroll, withholding,
income or other taxes, which are the sole and absolute responsibility of an
optionee or grantee under the Plan, are withheld or collected from such optionee
or grantee. In order to assist an optionee or grantee in paying all federal and
state taxes to be withheld or collected upon exercise of an option or award
which does not qualify as an Incentive Stock Option hereunder, the Committee, in
its absolute discretion and subject to such additional terms and conditions as
it may adopt, shall permit the optionee or grantee to satisfy such tax
obligation by (i) electing to have the Company withhold a portion of the shares
otherwise to be delivered upon exercise of such option or award with a fair
market value, determined in accordance with Section 5 herein, equal to such
taxes or (ii) delivering to the Company Common Stock other than the shares
issuable upon exercise of such option or award with a fair market value,
determined in accordance with Section 5, equal to such taxes.

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                  (b) The Committee shall have the authority, at the time of
grant of an option under the Plan or at any time thereafter, to approve tax
bonuses to designated optionees or grantees to be paid upon their exercise of
options or awards granted hereunder. The amount of any such payments shall be
determined by the Committee. The Committee shall have full authority in its
absolute discretion to determine the amount of any such tax bonus and the terms
and conditions affecting the vesting and payment thereafter.

12.      Additional Restrictions.

                  The Committee shall have full and complete authority to
determine whether all or any part of the Common Stock of the Company acquired
upon exercise of any of the options or awards granted under the Plan shall be
subject to restrictions on the transferability thereof or any other restrictions
affecting in any manner the optionee's or grantee's rights with respect thereto,
but any such restriction shall be contained in the agreement relating to such
options or awards.

13.      Ten Percent Shareholder Rule.

                  Notwithstanding any other provision in the Plan, if at the
time an option is otherwise to be granted pursuant to the Plan the optionee owns
directly or indirectly (within the meaning of Section 424(d) of the Code) Common
Stock of the Company possessing more than ten percent (10%) of the total
combined voting power of all classes of stock of the Company or its parent or
subsidiary corporations, if any (within the meaning of Section 422(b)(6) of the
Code), then any Incentive Stock Option to be granted to such optionee pursuant
to the Plan shall satisfy the requirements of Section 422(c)(5) of the Code, and
the option price shall be not less than 110% of the fair market value of the
Common Stock of the Company determined as described herein, and such option by
its terms shall not be exercisable after the expiration of five (5) years from
the date such option is granted.

14.      Non-Transferability.

                   No option may be sold, pledged, assigned, hypothecated,
transferred, or disposed of in any manner other than (i) by will or by the laws
of descent or distribution, or (ii) in the case of options that are not
Incentive Stock Options, to members of the optionee's immediate family or to one
or more trusts for the benefit of the optionee or members of his or her
immediate family, and the option may be exercised, during the lifetime of the
Optionee, only by the optionee or a permitted transferee.


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15.      Dilution or Other Adjustments.

                  If there shall be any change in the Common Stock through
merger, consolidation, reorganization, recapitalization, dividend in the form of
stock (of whatever amount), stock split or other change in the corporate
structure, appropriate adjustments in the Plan and outstanding options and
awards shall be made by the Committee. In the event of any such changes,
adjustments shall include, where appropriate, changes in the aggregate number of
shares subject to the Plan, the number of shares and the price per share subject
to outstanding options and awards and the amount payable upon exercise of
outstanding awards, in order to prevent dilution or enlargement of option or
award rights.

16.      Amendment or Discontinuance of Plan.

                  The Board of Directors may amend or discontinue the Plan at
any time. Subject to the provisions of Section 15 no amendment of the Plan,
however, shall without shareholder approval: (i) increase the maximum number of
shares under the Plan as provided in Section 2 herein, (ii) decrease the minimum
price provided in Section 5 herein, (iii) extend the maximum term under Section
6, or (iv) modify the eligibility requirements for participation in the Plan.
The Board of Directors shall not alter or impair any option or award theretofore
granted under the Plan without the consent of the holder of the option.

17.      Time of Granting.

                  Nothing contained in the Plan or in any resolution adopted or
to be adopted by the Board of Directors or by the shareholders of the Company,
and no action taken by the Committee or the Board of Directors (other than the
execution and delivery of an option or award agreement), shall constitute the
granting of an option or award hereunder.

18.      Effective Date and Termination of Plan.

                  (a) The Plan was approved by the Board of Directors on June
29, 1990 and shall be approved by the shareholders of the Company within twelve
(12) months thereof.

                  (b) Unless the Plan shall have been discontinued as provided
in Section 16 hereof, the Plan shall terminate June 29, 2005. No option or award
may be granted after such termination, but termination of the Plan shall not,
without the consent of the optionee or grantee, alter or impair any rights or
obligations under any option or award theretofore granted.

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