Trial Details Efficacy of Long-term HCL Therapy in Pediatric Patients With T1D


Researchers conducted a randomized clinical trial to test the efficacy of a hybrid closed-loop (HCL) system among pediatric patients with type 1 diabetes (T1D).

Six months of hybrid closed-loop (HCL) therapy significantly improved glycemic control and quality of life among children and adolescents with type 1 diabetes (T1D) when compared with conventional therapy, according to results of a randomized clinical trial. Findings were published in JAMA Pediatrics.

“The HCL system uses a control algorithm that delivers insulin based on continuous glucose monitoring (CGM) glucose measures,” authors explained. “However, meals must still be announced and an insulin bolus delivered according to meal carbohydrate content.” Previous research found this system improved glycemic measures, compared with standard therapy, in adults with T1D.

To evaluate the HCL’s long-term efficacy in children and adolescents with T1D and to address the psychosocial outcomes of use, researchers conducted a 6-month trial in Australia. Specifically, they compared the percentage of time in range (TIR) for the target glucose range (70 to 180 mg/dL) using HCL vs the currently available conventional therapies (continuous subcutaneous insulin infusion [CSII] or multiple daily injections [MDI] with or without CGM).

Between April 2017 and October 2019, investigators recruited 135 patients from 5 tertiary pediatric diabetes centers in Australia. Following a 5-week run-in phase, participants were randomly assigned to the control or intervention (HCL) groups for 26 weeks. In addition, masked CGM data were collected at baseline (3 weeks), midstudy (2 weeks), and study end (3 weeks), researchers said.

Mean (SD) participant age was 15.3 (3.1) years and the majority were girls (56%). Sixty-eight patients were randomized to the control group and 67 to the HCL group, while patients had a mean diabetes duration of 7.7 (4.3) years and a mean glycated hemoglobin (HbA1C) of 64(11) mmol/mol.

Analyses revealed:

  • In the intention-to-treat analyses, TIR increased from a mean of 53.1% (13%) at baseline to 62.5% (12%) at the end of the study in the HCL group and from 54.6% (12.5%) to 56.1% (12.2%) in the control group, with a mean adjusted difference between the 2 groups of 6.7% (95% CI, 2.7%-10.8%; P = .002)
  • This mean difference equated to an additional 1.6 hours per day in target range on HCL
  • HCL therapy also reduced the time that patients spent in a hypoglycemic (<70 mg/dL) range (difference, −1.9%; 95% CI, −2.5% to −1.3%) and improved glycemic variability (coefficient of variation difference, −5.7%; 95% CI, −10.2% to −0.9%)
  • HCL therapy was associated with improved diabetes-specific quality of life (difference, 4.4 points; 95% CI, 0.4-8.4 points), with no change in diabetes distress
  • There were no episodes of severe hypoglycemia or diabetic ketoacidosis in either group

“In our study, the improvement in TIR was seen across both day and night and was associated with a reduction in hypoglycemia and glycemic variability, albeit with no reduction in hyperglycemia,” authors wrote.

Researchers hypothesized improved quality of life scores reported among HCL uses could be due to factors like reduced worry, increased confidence and trust in the system with improved glycemic control, and increased ownership of diabetes management.

As the trial was conducted by tertiary centers with technology expertise, results may not be generalizable to the wider public, marking a limitation. In addition, researchers were unable to assess the degree of engagement with CGM devices of participants in the control group.

“To our knowledge, this is the first randomized clinical trial in youth with T1D to provide conclusive evidence that HCL improves glycemic outcomes and quality of life in youth with T1D,” authors concluded. “The HCL system represents an important step in the pursuit of technological advancements toward a fully automated closed-loop system.”


Abraham MB, de Bock M, Smith GJ, et al. Effect of a hybrid closed-loop system on glycemic and psychosocial outcomes in children and adolescents with type 1 diabetes: a randomized clinical trial. JAMA Pediatr. Published online October 11, 2021. doi:10.1001/jamapediatrics.2021.3965

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