Trial of Hybrid Closed-Loop Control in Young Children with Type 1 Diabetes

N Engl J Med. 2023 Mar 16;388(11):991-1001. doi: 10.1056/NEJMoa2210834.


Background: Closed-loop control systems of insulin delivery may improve glycemic outcomes in young children with type 1 diabetes. The efficacy and safety of initiating a closed-loop system virtually are unclear.

Methods: In this 13-week, multicenter trial, we randomly assigned, in a 2:1 ratio, children who were at least 2 years of age but younger than 6 years of age who had type 1 diabetes to receive treatment with a closed-loop system of insulin delivery or standard care that included either an insulin pump or multiple daily injections of insulin plus a continuous glucose monitor. The primary outcome was the percentage of time that the glucose level was in the target range of 70 to 180 mg per deciliter, as measured by continuous glucose monitoring. Secondary outcomes included the percentage of time that the glucose level was above 250 mg per deciliter or below 70 mg per deciliter, the mean glucose level, the glycated hemoglobin level, and safety outcomes.

Results: A total of 102 children underwent randomization (68 to the closed-loop group and 34 to the standard-care group); the glycated hemoglobin levels at baseline ranged from 5.2 to 11.5%. Initiation of the closed-loop system was virtual in 55 patients (81%). The mean (±SD) percentage of time that the glucose level was within the target range increased from 56.7±18.0% at baseline to 69.3±11.1% during the 13-week follow-up period in the closed-loop group and from 54.9±14.7% to 55.9±12.6% in the standard-care group (mean adjusted difference, 12.4 percentage points [equivalent to approximately 3 hours per day]; 95% confidence interval, 9.5 to 15.3; P<0.001). We observed similar treatment effects (favoring the closed-loop system) on the percentage of time that the glucose level was above 250 mg per deciliter, on the mean glucose level, and on the glycated hemoglobin level, with no significant between-group difference in the percentage of time that the glucose level was below 70 mg per deciliter. There were two cases of severe hypoglycemia in the closed-loop group and one case in the standard-care group. One case of diabetic ketoacidosis occurred in the closed-loop group.

Conclusions: In this trial involving young children with type 1 diabetes, the glucose level was in the target range for a greater percentage of time with a closed-loop system than with standard care. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases; PEDAP number, NCT04796779.).

Publication types

  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Blood Glucose Self-Monitoring
  • Blood Glucose* / analysis
  • Child
  • Child, Preschool
  • Diabetes Mellitus, Type 1* / blood
  • Diabetes Mellitus, Type 1* / drug therapy
  • Glycated Hemoglobin / analysis
  • Humans
  • Hypoglycemic Agents* / administration & dosage
  • Hypoglycemic Agents* / adverse effects
  • Hypoglycemic Agents* / therapeutic use
  • Insulin Infusion Systems* / adverse effects
  • Insulin* / administration & dosage
  • Insulin* / adverse effects
  • Insulin* / therapeutic use


  • Blood Glucose
  • Glycated Hemoglobin
  • Hypoglycemic Agents
  • Insulin

Associated data