A Study of t:Slim X2 With Control-IQ Technology

After consent is signed, eligibility will be assessed. Eligible participants not currently
using an insulin pump and Dexcom CGM with minimum data requirements will initiate a run-in
phase of 2-4 weeks that will be customized based on whether the participant is already a pump
or CGM user. Participants who skip or successfully complete the run-in will be randomly
assigned 3:1 to the use of closed-loop control (CLC group) using t:slim X2 with Control-IQ
Technology vs. Standard of Care (SC) for 16 weeks. The Standard of Care (SC) group will be
offered to transition to use CLC and the experimental arm will extend their use of CLC for 12
weeks.

Inclusion Criteria:

1. Clinical diagnosis, based on investigator assessment, of type 1 diabetes for at least
one year and using insulin for at least 6 months

2. Familiarity and use of a carbohydrate ratio for meal boluses.

3. Age ≥ 6 and ≤ 13 years old

4. For females, not currently known to be pregnant If female and sexually active, must
agree to use a form of contraception to prevent pregnancy while a participant in the
study. A negative serum or urine pregnancy test will be required for all females of
child-bearing potential. Participants who become pregnant will be discontinued from
the study. Also, participants who during the study develop and express the intention
to become pregnant within the timespan of the study will be discontinued.

5. Living with one or more parent/legal guardian knowledgeable about emergency procedures
for severe hypoglycemia and able to contact emergency services and study staff.

6. Willingness to suspend use of any personal closed loop system that they use at home
for the duration of the clinical trial once the study CGM is in use

7. Investigator has confidence that the participant can successfully operate all study
devices and is capable of adhering to the protocol

8. Willingness to switch to lispro (Humalog) or aspart (Novolog) if not using already,
and to use no other insulin besides lispro (Humalog) or aspart (Novolog) during the
study for participants using to t:slim X2. This includes:

- Participants randomized to Control IQ

- Participants on the SC group on MDI treatment that will be provided a Tandem pump
to switch to CSII

- Participates that are already in CSII randomized to SC during the extension phase
when transition to Control IQ

9. Total daily insulin dose (TDD) at least 10 U/day

10. Willingness not to start any new non-insulin glucose-lowering agent during the course
of the trial

11. Participant and parent(s)/guardian(s) willingness to participate in all training
sessions as directed by study staff.

Exclusion Criteria:

1. Concurrent use of any non-insulin glucose-lowering agent other than metformin
(including GLP-1 agonists, Symlin, DPP-4 inhibitors, SGLT-2 inhibitors,
sulfonylureas).

2. Hemophilia or any other bleeding disorder

3. A condition, which in the opinion of the investigator or designee, would put the
participant or study at risk (specified on the study procedure manual)

4. Participation in another pharmaceutical or device trial at the time of enrollment or
during the study

5. Employed by, or having immediate family members employed by Tandem Diabetes Care,
Inc., or having a direct supervisor at place of employment who is also directly
involved in conducting the clinical trial (as a study investigator, coordinator,
etc.); or having a first-degree relative who is directly involved in conducting the
clinical trial