PS230005 Control-IQ 1.5 Post-Approval Study

Inclusion Criteria:

• Self-reported type 1 diabetes who have been prescribed the Control-IQ 1.5 system inthe t:slim X2 or Mobi insulin pump

• Age 2 to <6 years at time of screening

• Using an insulin approved for use in the pump

• Using an iCGM sensor approved for use with the pump

• Agreement to use Control-IQ technology 1.5, and to continue use for at least 12consecutive months after study enrollment.

• Agree to provide HbA1c result, obtained within the 6-month period prior toenrollment.

• Ability for parent/guardian to respond to alerts and alarms, and to provide basicdiabetes self-management.

• Reside full-time in the United States.

• Willingness to download the t:connect Mobile application to their smartphone andkeep it active throughout the study if using a Tandem t:slim X2 pump. Participantswho are unable to use the t:connect mobile application must be willing to manuallyupload their insulin pump data to Tandem Source every three months and at thecompletion of the study.

• Participant's parent/guardian has read, understood and agreed to participate in thestudy, and has electronically signed the Informed Consent Form (ICF).

Exclusion Criteria:

• Use of any glucose-lowering therapy other than insulin.

• A medical or other condition, or medications being taken that in the investigator'sjudgement would be a safety concern for participation in the study.