-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001209191-04-022867.txt : 20040430
<SEC-HEADER>0001209191-04-022867.hdr.sgml : 20040430
<ACCEPTANCE-DATETIME>20040430151716
ACCESSION NUMBER:		0001209191-04-022867
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040421
FILED AS OF DATE:		20040430

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			DIAMETRICS MEDICAL INC
		CENTRAL INDEX KEY:			0000895380
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTROMEDICAL & ELECTROTHERAPEUTIC APPARATUS [3845]
		IRS NUMBER:				411663185
		STATE OF INCORPORATION:			MN
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2658 PATTON RD
		CITY:			ROSEVILLE
		STATE:			MN
		ZIP:			55113
		BUSINESS PHONE:		6516398035

	MAIL ADDRESS:	
		STREET 1:		2658 PATTON ROAD
		CITY:			ROSEVILLE
		STATE:			MN
		ZIP:			55113

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Bay Investment Group, L.L.C.
		CENTRAL INDEX KEY:			0001288735
		STATE OF INCORPORATION:			DE

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21982
		FILM NUMBER:		04769538

	BUSINESS ADDRESS:	
		STREET 1:		200 WEST MADISON STREET, 25TH FLOOR
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
		BUSINESS PHONE:		312-750-8444

	MAIL ADDRESS:	
		STREET 1:		200 WEST MADISON STREET, 25TH FLOOR
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>c85026_02big.xml
<DESCRIPTION>MAIN DOCUMENT DESCRIPTION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2004-04-21</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000895380</issuerCik>
        <issuerName>DIAMETRICS MEDICAL INC</issuerName>
        <issuerTradingSymbol>DMED</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001288735</rptOwnerCik>
            <rptOwnerName>Bay Investment Group, L.L.C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>20 WEST MADISON STREET</rptOwnerStreet1>
            <rptOwnerStreet2>25TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60606</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>978834</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>858169</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Common Stock Warrants</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.34</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2003-12-31</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-04-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>615870</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Common Stock Warrants</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.34</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2004-03-31</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-04-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>615870</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Common Stock Warrants</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.34</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2004-06-30</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-04-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>615871</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Common Stock Warrants</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.34</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2003-12-31</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-04-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>540197</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Common Stock Warrants</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.34</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2004-03-31</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-04-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>540197</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Common Stock Warrants</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.34</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2004-06-30</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-04-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>540197</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">858,169 of these shares are owned directly by BCC Amalgamated, L.L.C. Bay Investment Group, L.L.C. owns a majority of the membership interests in BCC Amalgamated, L.L.C.</footnote>
        <footnote id="F2">Warrants to purchase 540,197 shares of common stock of the Issuer are owned directly by BCC Amalgamated, L.L.C.  Bay Investment Group, L.L.C. owns a majority of the membership interests in BCC Amalgamated, L.L.C.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Marshall E. Eisenberg, not individually, but solely as a co-Trustee of the R.A. Trust #25, a partner of R.A. Investment Group, a member of the Reporting Person</signatureName>
        <signatureDate>2004-04-30</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----