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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2013-11-13</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001438133</issuerCik>
        <issuerName>TANDEM DIABETES CARE INC</issuerName>
        <issuerTradingSymbol>TNDM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001340660</rptOwnerCik>
            <rptOwnerName>HLM VENTURE PARTNERS II, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>222 BERKELEY STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001591541</rptOwnerCik>
            <rptOwnerName>HLM Venture Associates II, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>222 BERKELEY STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001025665</rptOwnerCik>
            <rptOwnerName>CAHILL EDWARD L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O HLM VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>222 BERKELEY STREET</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001242813</rptOwnerCik>
            <rptOwnerName>GRUA PETER J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O HLM VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>222 BERKELEY STREET</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001225960</rptOwnerCik>
            <rptOwnerName>RAY RUSSELL T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O HLM VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>222 BERKELEY STREET</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Series C Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.00</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>223684</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series D Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.00</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1230374</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Preferred Stock Warrant</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.40</value>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2021-08-17</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Series D Preferred Stock</value>
                    <footnoteId id="F5"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>87662</value>
                    <footnoteId id="F5"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Preferred Stock Warrant</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.40</value>
                <footnoteId id="F6"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2022-05-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Series D Preferred Stock</value>
                    <footnoteId id="F6"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>21915</value>
                    <footnoteId id="F6"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Preferred Stock Warrant</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.40</value>
                <footnoteId id="F7"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2022-07-17</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Series D Preferred Stock</value>
                    <footnoteId id="F7"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>33014</value>
                    <footnoteId id="F7"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The securities are immediately convertible.</footnote>
        <footnote id="F2">The expiration date is not relevant to the conversion of these securities.</footnote>
        <footnote id="F3">The reported securities are owned by HLM Venture Partners II, L.P. HLM Venture Associates II, L.L.C. (the &quot;General Partner&quot;), and  Edward L. Cahill, Peter J. Grua and Russell T. Ray, the managing members of the General Partner, may be deemed to share voting and dispositive power over the reported securities but each disclaims beneficial ownership in the securities held by HLM Venture Partners II, L.P., except to the extent of their pecuniary interest therein.</footnote>
        <footnote id="F4">The warrants are immediately exercisable.</footnote>
        <footnote id="F5">Upon the consummation of the Issuer's initial public offering, these warrants will automatically become exercisable for 52,316 shares of the Issuer's common stock at an exercise price of $4.40 per share.</footnote>
        <footnote id="F6">Upon the consummation of the Issuer's initial public offering, these warrants will automatically become exercisable for 13,078 shares of the Issuer's common stock at an exercise price of $4.40 per share.</footnote>
        <footnote id="F7">Upon the consummation of the Issuer's initial public offering, these warrants will automatically become exercisable for 19,702 shares of the Issuer's common stock at an exercise price of $4.40 per share.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ David B. Berger, Attorney-in-Fact for HLM Venture Partners II, L.P.</signatureName>
        <signatureDate>2013-11-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ David B. Berger, Attorney-in-Fact for HLM Venture Associates II, L.L.C.</signatureName>
        <signatureDate>2013-11-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ David B. Berger, Attorney-in-Fact for Edward L. Cahill</signatureName>
        <signatureDate>2013-11-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ David B. Berger, Attorney-in-Fact for Peter J. Grua</signatureName>
        <signatureDate>2013-11-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ David B. Berger, Attorney-in-Fact for Russell T. Ray</signatureName>
        <signatureDate>2013-11-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
