Safety Evaluation of an Advanced Hybrid Closed Loop System Using Lyumjev With the Tandem t:Slim X2 Insulin Pump With Control-IQ Technology in Adults, Adolescents and Children With Type 1 Diabetes

• Age 6 to \<81 years

• Diagnosis of type 1 diabetes for at least 1 year

• Currently using Control-IQ technology for at least 3 months, with CGM data recorded indicative of system use (active closed loop) for at least 85% of the possible time in 14 days prior to enrollment

• Total daily insulin dose (TDD) at least 2 U/day

• HbA1c \< 10.5%

• Residing full-time in the United States, with no anticipated travel outside the United States during the period of study participation.

• For participants \<18 years old, living with one or more parent/legal guardian knowledgeable about emergency procedures for severe hypoglycemia and able to contact the participant in case of an emergency, and willing to use the Dexcom Follow app (with push notifications turned on) for the duration of the study.

• If \>18 years old, participant has someone who lives within 30 minutes of them who is willing to be contacted if the study team can't reach the participant in case of a suspected medical emergency.

• Participant has agreed to participate in the study; and has read, understood and signed the informed consent form (ICF) and assent, if applicable; and has agreed to follow all study procedures, including:

∙ suspending use of any personal CGM for the duration of the clinical trial once the study CGM is in use

‣ switching to or continuing to use Humalog during the lead-in period

‣ switching to Lyumjev for the main study period.

‣ willing and able to perform the study exercise and meal challenges.

⁃ Investigator has confidence that the participant can successfully operate all study devices and is capable of adhering to the protocol, including ability to respond to alerts and alarms, and to provide basic diabetes self-management.

⁃ Participant and/or parent/legal guardian have the ability to read and understand English