Hybrid Closed-Loop System Improves Glycemic Control in Children with T1D

Roman Havorka, PhD

New research suggests a hybrid closed-loop system led to significant improvements in glycemic control in young children with type 1 diabetes (T1D), without subsequently increasing the amount of time spent in hypoglycemia.

“Given the low glycated hemoglobin levels at baseline, the improved levels in our trial are noteworthy, because higher baseline glycated hemoglobin levels are associated with a greater reduction in the level when hybrid closed-loop therapy is used,” wrote study author Roman Hovorka, PhD, University of Cambridge Metabolic Research Laboratories.

A team of investigators hypothesized the use of the Cambridge closed-loop algorithm for 16 weeks in children aged 1 - 7 years with T1D would “improve glycemic control, as compared with sensor-augmented pump therapy, and have an acceptable safety profile.”

Patients were recruited from outpatient clinics at diabetes centers in Austria, Luxembourg, and the United Kingdom. The key inclusion criteria were a diagnosis of T1D at least 6 months prior to enrollment, receipt of insulin-pump therapy for ≥3 months before enrollment, and a glycated hemoglobin level of no more than 11.0% at screening.

Investigators noted the hybrid closed-loop system consisted of an unlocked smartphone with an application running the algorithm automatically adjusting insulin delivery by the insulin pump on the basis of real-time senior glucose readings.

They included patients received their treatment in two 16-week periods in random order, where the closed-loop system was compared to sensor-augmented pump therapy as control. The primary endpoint was considered the between-treatment difference in the percentage of time spent in the target glucose range (70 - 190 mg per deciliter).

Other key endpoints included the percentage of time spent in a hyperglycemic state (glucose level, >180 mg per deciliter), glycated hemoglobin level, mean sensor glucose level, and the percentage of time spent in a hypoglycemic state (glucose level <70 mg per deciliter).

From May 2019 - June 2020, a total of 81 children were enrolled, but following withdrawals, 74 children underwent randomization. The mean age of participants was 5.6 ±1.6 years, while the baseline glycated hemoglobin level was 7.3±0.7%

Data show the percentage of time in the target glucose range was 8.7 percentage points (95% CI, 7.4 - 9.9) higher during the closed-loop period, compared to control (P <.001).

Additionally, the mean adjusted difference in the percentage of time spent in a hyperglycemic state was -8.5 percentage points (95% CI, -9.9 to -7.1), while the difference in glycated hemoglobin level was -0.4 percentage points (95% CI, -0.5 to -0.3).

Investigators noted a “significantly lower glycated hemoglobin level at the end of the closed-loop period than at the end of the sensor- augmented pump period (P<0.001).”

Further, the mean sensor glucose level was significantly lower during the closed-loop period, than the sensor augmented pump period (mean adjusted difference, -12.3 mg per deciliter; 95% CI, -14.8 to -9.8; P <.001 for all comparisons.

Lastly, investigators observed the time spent in a hypoglycemic state did not differ significantly between the two interventions (P = .74).

The study, “Randomized Trial of Closed-Loop Control in Very Young Children with Type 1 Diabetes,” was published in The New England Journal of Medicine.