The International Diabetes Closed Loop (iDCL) Trial: Clinical Acceptance of the Artificial Pancreas (DCLP3 Extension)

This is a 3-month extension study (DCLP3 Extension) following a primary trial (DCLP3 or NCT03563313) to assess efficacy and safety of a closed loop system (t:slim X2 with Control-IQ Technology) in a large randomized controlled trial. Upon completion of the NIH 3-month extension study, subjects will be invited to participate in a continued use phase with Control-IQ Technology, funded by Tandem Diabetes Care, until the equipment has received FDA approval for commercial use.

Participants in the 6 month primary trial (DCLP3) will be invited to continue in this 3-month extension study (DCLP3 Extension) following completion of the primary trial. The closed-loop control (CLC) Intervention Group participants from the primary trial will be randomly assigned to continue CLC or to switch to Predictive Low-Glucose Suspend (PLGS) therapy with t:slim X2 with Basal-IQ and Dexcom G6 for 3 months. The Sensor-Augmented Pump (SAP) Control Group participants from the primary trial will be assigned to CLC using t:slim X2 with Control-IQ Technology and Dexcom G6 (CGM) for 3 months. Upon completion of the extension study, subjects will be invited to participate in continued use of the Control-IQ Technology until the equipment has received FDA approval for commercial use.

This extension phase has two separate objectives:

Objective 1: Among participants who used CLC in the primary trial: the primary efficacy outcome for the randomized controlled trial (RCT) is time in target range 70-180 mg/dL measured by CGM in CLC group vs. PLGS group over 3 months. Safety outcomes also will be assessed Objective 2: Among participants who used SAP in the primary trial: the primary outcome is to obtain additional safety data. Efficacy also will be assessed as a pre-post within participant analysis

Note: Primary Trial (DCLP3) is NCT03563313

Eligibility Criteria:
Inclusion Criteria:

1. Successful completion of the original 6-month RCT within the prior 14 days
2. 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 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.
3. 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.
4. Willingness to not use a personal CGM for the duration of the study
5. Investigator has confidence that the participant can successfully operate all study devices and is capable of adhering to the protocol
6. Willingness to use only lispro (Humalog) or aspart (Novolog), and to use no other insulin during the study.
7. Willingness not to start any new non-insulin glucose-lowering agent during the course of the trial

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
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., Dexcom, Inc., or TypeZero Technologies, LLC, 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