Closed Loop Insulin Improves Time in Range, Rates of Dysglycemia in Type 1 Diabetes

John Lum, MS

A closed-loop control (CLC) insulin delivery system could be safe and effective for use in adolescents and young adults with type 1 diabetes, according to the results of the International Diabetes Closed-Loop (iDCL) Trial.

Results of the study indicated use of a CLC for 6 months resulted in improved time in range and reduced incidence of hypoglycemia in younger patients with type 1 diabetes.

“We found that this sample of adolescents and young adults successfully used the CGM more than 90% of the time during the 6-month trial and the closed-loop system was active 89% of the time," said study investigator John Lum, MS, of the Jaeb Center for Health Research and member of the iDCL Trial Research Group, in a statement.

To further evaluate the efficacy and safety of a CLC insulin delivery system, the current study was designed as a prespecified subanalysis of outcomes among patients within the iDCL trial. The original iDCL trial included patients with type 1 diabetes who were randomized in a 2:1 ratio to the Tandem Control-IQ CLC or a sensor augmented pump and followed for a period of 6 months.

As part of their original trial, follow-up visits occurred at weeks 2, 6, 13, and 26. Primary outcomes of interest for the trial included CGM-derived glycemic metrics, mean glucose, hyperglycemia, hypoglycemia, HbA1c changes, and incidence of adverse events. Adverse events of interest included those occurring in association with device or procedure, severe hypoglycemia, diabetic ketoacidosis, and hyperglycemia.

In total, 63 participants were identified for inclusion in this secondary analysis. The age of participants ranged from 14-24 years with a mean age of 17 years. The study cohort was 43% female, 83% identified as white, and 11% were considered Hispanic or Latino. At baseline mean type 1 diabetes duration was 7 years, mean HbA1c was 8.1% (65 mmol/mol), and 19% were pump naive. Of note, all 63 participants completed the 6-month follow-up period.

Among those in the CLC group, investigators noted time in range increased by 13% compared to those in the augmented pump group (95% CI, 9-16; P <.001). Investigators pointed out this was a reflection of a reduction in time spent at greater than 180 mg/dL (adjusted difference -12% [-2.9 hours per day], P <.001). Additionally, time spent at less than 70 mg/dL decreased by 1.6% in the CLC group versus 0.3% in the augmented pump arm (adjusted difference -0.7% [-10 min/day], 95% CI, -1.0 to -0.2%, P=.002).

Over the 6-month follow-up period, CLC use achieved 89%. Overall, the mean adjusted difference after the follow-up period was 0.30% among the CLC group versus the augmented pump group (95% CI, -0.67 to 0.08, P=.13). Investigators noted there was one episode of diabetic ketoacidosis in the CLC group during the follow-up period.

"Multiple Automated Insulin Delivery (AID) systems using different algorithms have been developed in the past decade for patients with type 1 diabetes. Almost all of the systems have shown significant reductions in nocturnal hypoglycemia. The iDCL multicenter trial done in young adults and adolescents with T1D reported in this issue of DTT further advances the use of hybrid closed-loop system by increasing the time-in-range, especially during the night," added Lum.

This study, “Closed-Loop Insulin Therapy Improves Glycemic Control in Adolescents and Young Adults: Outcomes from the International Diabetes Closed-Loop Trial,” was published in Diabetes Technology and Therapeutics.