Sec Form 4 Filing - ROEDER DOUGLAS A @ TANDEM DIABETES CARE INC - 2021-05-27

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) 05/27/2021 (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 05/27/2021 M 1,892 A $ 0 1,892 D Common Stock 990,330 I See Footnote ( 1 ) Common Stock 9,670 I See Footnotes ( 2 )

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 Security (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 Restricted Stock Unit ( 3 ) ( 4 ) 05/27/2021 M( 5 ) 1,892 ( 6 ) ( 6 ) Common Stock 1,892 $ 0 0 D

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/ David B. Berger, Attorney-in-Fact for Douglas A. Roeder 06/01/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Reporting Person is a managing member of Delphi Management Partners VIII, L.L.C. ("DMP"), the general partner of Delphi Ventures VIII, L.P. As a managing member of DMP, the Reporting Person shares voting and investment power over the securities held by Delphi Ventures VIII, L.P. and may be deemed to have indirect beneficial ownership of such shares. The Reporting Person disclaims beneficial ownership of such securities held by Delphi Ventures VIII, L.P., except to the extent of his proportionate pecuniary interest therein. ( 2 )The Reporting Person is a managing member of Delphi Management Partners VIII, L.L.C. ("DMP"), the general partner of Delphi BioInvestments VIII, L.P. As a managing member of DMP, the Reporting Person shares voting and investment power over the securities held by Delphi BioInvestments VIII, L.P. and may be deemed to have indirect beneficial ownership of such shares. The Reporting Person disclaims beneficial ownership of such securities held by Delphi BioInvestments VIII, L.P., except to the extent of his proportionate pecuniary interest therein. ( 3 )Granted pursuant to the Tandem Diabetes Care, Inc. 2013 Stock Incentive Plan (the 2013 Plan). ( 4 )Each restricted stock unit (RSU) represents a contingent right to receive one share of common stock of the Company. ( 5 )This RSU award was granted on May 27, 2020. 100% of the RSU vested on May 27, 2021. ( 6 )RSU vest as to one-hundred percent (100%) of the total number of shares subject to the RSU on 5/27/2021.

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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