Sec Form 4 Filing - ROEDER DOUGLAS A @ TANDEM DIABETES CARE INC - 2021-10-15

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person ROEDER DOUGLAS A 2. Issuer Name and Ticker or Trading Symbol TANDEM DIABETES CARE INC [ TNDM] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O DELPHI VENTURES,, 63 BOVET ROAD, SUITE 351 3. Date of Earliest Transaction (MM/DD/YY) 10/15/2021 (Street) SAN MATEO, CA94402 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 10/15/2021 J( 1 )( 5 ) V 1,000,000 D $ 0 0 I See footnote ( 2 ) Common Stock 10/15/2021 J( 1 )( 5 ) V 11,568 A $ 0 13,460 I See footnote ( 3 ) Common Stock 10/15/2021 J( 1 )( 5 ) V 11,568 D $ 0 1,892 I See footnote ( 3 ) Common Stock 10/15/2021 J( 1 )( 5 ) V 3,766 A $ 0 3,766 I See Footnote ( 4 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Securit y (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ROEDER DOUGLAS A C/O DELPHI VENTURES, 63 BOVET ROAD, SUITE 351 SAN MATEO, CA94402 X Signatures /s/ Matthew T. Potter, by power of attorney for Douglas A. Roeder 10/20/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents a pro rata distribution, not for additional consideration, by Delphi BioInvestments VIII, L.P. ("DB VIII") and Delphi Ventures VIII, L.P. ("DV VIII") to their respective partners, and by Delphi Management Partners VIII, L.L.C. ("DMP"), the general partner of each of DB VIII and DV VIII, to its members and assignees, as applicable. This distribution was made pursuant to a Rule 10b5-1 distribution plan. ( 2 )Shares are held directly by DB VIIII and DV VIII. The Reporting Person is a managing member of DMP. As a managing member of DMP, the Reporting Person shares voting and investment power over the securities held by DB VIII and DV VIII, and may be deemed to have indirect beneficial ownership of such shares. The Reporting Person disclaims beneficial ownership of such securities, except to the extent of his proportionate pecuniary interest therein. ( 3 )Shares are held directly by DMP. The Reporting Person is a managing member of DMP. As a managing member of DMP, the Reporting Person shares voting and investment power over the securities held by DMP, and may be deemed to have indirect beneficial ownership of such shares. The Reporting Person disclaims beneficial ownership of such securities, except to the extent of his proportionate pecuniary interest therein. ( 4 )The shares are held directly by The Roeder Family Trust dated 5/29/08, of which the Reporting Person is trustee. ( 5 )This transaction is being voluntarily reported, reflects a change in form of beneficial ownership of the Reporting Person and is exempt from Section 16 pursuant to Rule 16a-13 under the Securities Exchange Act of 1934.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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