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
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.