13D Filing: Kim D Blickenstaff and Tandem Diabetes Care Inc (NASDAQ:TNDM)

The third paragraph following the outstanding option table in Item 6 of the Previously Amended Schedule
13D is hereby amended and restated in its entirety to read as follows:

On March 1, 2017, in connection with the Public Offering,
the Reporting Persons, together with other officers, directors and stockholders of the Issuer, entered into a Lock-Up Agreement. Pursuant to such Lock-Up Agreement, the
Reporting Persons agreed that they will not sell, transfer or dispose of, directly or indirectly, any of the Common Stock or securities convertible into or exercisable or exchangeable for Common Stock for a period of 90 days after the date of the
final prospectus for the Public Offering. This summary description does not purport to be complete, and is qualified in its entirety by the Form of Lock-Up Agreement attached as Exhibit C to the Form of
Underwriting Agreement filed as Exhibit 1.1 to the Registration Statement on Form S-1 filed with the SEC on March 22, 2017, which is incorporated herein by reference.