The DCLP5 study aimed to assess the efficacy and safety of a closed loop control (CLC) insulin pump system in a randomized controlled trial for children with type 1 diabetes. Eligible participants not using an insulin pump or Dexcom G4, G5, or G6 continuous glucose monitoring (CGM), initiated a run-in phase of 2 to 4 weeks that was customized based on whether the participant was already a pump or CGM user. Participants who skipped or successfully completed the run-in were randomly assigned 3:1 to the use of closed-loop control (CLC group) using t:stim X2 with Control-IQ Technology and Dexcom G6 CGM versus a control group for 16 weeks during the main phase. The control group could later transition to the CLC group and the experimental arm could extend for an additional 12 weeks during the extension phase.

Primary objective: Assess the efficacy and safety of the closed loop system compared with the standard of care.

Primary outcome measure: Time in target range 70-180 mg/dL measured by CGM in CLC group versus control group.

Secondary outcome measures:

• CGM-measured percent above or below the target range
• CGM-measured mean glucose
• HbA1c levels
• Glucose variability measured with the coefficient of variation (CV)

Inclusion criteria:

• Clinical diagnosis, based on investigator assessment, of type 1 diabetes for at least one year and using insulin for at least 6 months
• Familiarity and use of a carbohydrate ratio for meal boluses
• Age ≥ 6 and ≤ 13 years old
• Weight ≥ 25 kg and ≤ 140 kg
• Willingness to suspend use of any personal CGM for the duration of the clinical trial
• 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
• Total daily insulin dose (TDD) at least 10 U/day
• Willingness not to start any new non-insulin glucose-lowering agent during the course of the trial
• Participant and parent(s)/guardian(s) willingness to participate in all training sessions as directed by study staff

Exclusion criteria:

• Concurrent use of any non-insulin glucose-lowering agent other than metformin (including GLP-1 agonists, Symlin, DPP-4 inhibitors, SGLT-2 inhibitors, sulfonylureas)
• Hemophilia or any other bleeding disorder
• Participation in another pharmaceutical or device trial at the time of enrollment or during the study

After completion of the 16-week trial involving children with type 1 diabetes, a greater percentage of time was spent in the target glucose level for those using the closed-loop system than those in the control group.

Data generated from this study are available externally outside of the NIDDK Central Repository. Please navigate to the external repository and follow the policies and procedures to access data associated with this study: https://public.jaeb.org/dataset/535