<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2022-01-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001401040</issuerCik>
        <issuerName>DiaMedica Therapeutics Inc.</issuerName>
        <issuerTradingSymbol>DMAC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001759855</rptOwnerCik>
            <rptOwnerName>Parsons James T.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>TWO CARLSON PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 260</rptOwnerStreet2>
            <rptOwnerCity>MINNEAPOLIS</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55447</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Voting Common Shares, no par value per share</value>
            </securityTitle>
            <transactionDate>
                <value>2022-01-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>16773</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.58</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>38509</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares are issuable upon settlement of deferred stock units granted under the DiaMedica Therapeutics Inc. 2019 Omnibus Incentive Plan in lieu of cash retainer fees in the aggregate amount of $60,000.</footnote>
        <footnote id="F2">Amount reflects the cancellation of 211 shares underlying deferred share units granted in lieu of Board committee retainers due to a change in Board committee memberships.</footnote>
        <footnote id="F3">Includes 3,850 voting common shares issuable upon settlement of deferred share units granted under the DiaMedica Therapeutics Inc. Deferred Share Unit Plan and 32,409 shares issuable upon settlement of deferred stock units granted under the DiaMedica Therapeutics Inc. 2019 Omnibus Incentive Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Amy Culbert, attorney-in-fact</signatureName>
        <signatureDate>2022-01-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
