Extends time in target glucose range by 2.6 hours

In a randomized trial of children with type 1 diabetes, a closed-loop insulin delivery system—the so-called artificial pancreas—achieved better glycemic control for longer periods than sensor-augmented insulin pumps.

The findings from the 16-week trial were published in The New England Journal of Medicine and were initially reported at the 13th International conference on Advanced Technologies and Treatments for Diabetes in Madrid last February.

Patients in the closed-loop group increased the percentage of time that glucose levels were in the target range of 70 to 180 mg/dL from a mean of 53 ±17% at baseline to 67 ±10% versus 51 ±16% to 55 ±13% in the control group, “with a mean adjusted difference (the value in the closed-loop group minus the value in the control group) of 11 percentage points (95% confidence interval [CI], 7 to 14; P <0.001),” wrote Marc D. Breton, PhD, of the University of Virginia Center for Diabetes Technology in Charlottesville, and a multi-center group of colleagues. That works out to “2.6 hours less per day in a hyperglycemic state with closed-loop control.”

The trial recruited 101 patients ages 6 to 13 and assigned 78 to the closed-loop group and 23 to the control group (sensor-augmented insulin pump). “Before the trial, 81 patients (80%) had been using insulin pumps, and 20 patients (20%) had been receiving multiple daily injections; 93 patients (92%) had been using a continuous glucose monitor,” they wrote.

At 16 weeks, 100 patients had completed the trial and during the 16 weeks there were 19 unscheduled visits in the closed-loop group versus 1 unscheduled visit in the control group. In the closed-loop cohort, the “median percentage of time with the system was in the closed-loop mode was 93% … In the control group, the median percentage of continuous glucose monitor use over the 16 weeks was 96% … and all patients … were used a sensor-augmented pump at the end of 16 weeks.”

Among the findings:

  • From 6 a.m. to midnight, closed-loop patients were in target glucose level 63% of the time versus 56% in the control group.
  • Nighttime values were 80% and 54% (closed-loop versus control group).
  • Between group difference in glycated hemoglobin level at 16 weeks was −0.4% (NS).

“The glycemic target of a glycated hemoglobin level of less than 7% (as recommended by the American Diabetes Association) was met in 39 patients (51%) in the closed-loop group and in 4 patients (18%) in the control group at 16 weeks,” Breton and colleagues wrote. “The goal of a percentage of time with the blood glucose level in target range (70 to 180 mg per deciliter) of at least 70% plus a percentage of time with the glucose level below 70 mg per deciliter of less than 4% was attained in 33 patients (42%) in the closed-loop group and in 3 patients (14%) in the control group.”

Overall there were no serious adverse events, including no reports of severe hypoglycemia or diabetic ketoacidosis in the closed-loop group. That said, there were More AEs “primarily associated with hyperglycemia and ketonemia caused by pump infusion set failure, were reported in the closed-loop group than in the control group. Because the control group mostly used the same pump and infusion set as the closed-loop group, this difference probably reflects variation in reporting, possibly related to instructions to patients using the closed-loop system to contact staff at their trial site about device problems.”

The authors noted a number of limitations including the very low baseline hypoglycemia rate in both groups, “which, in addition to the fact that most of the patients in the control group used a pump with a predictive low-glucose suspend feature, limited the ability of the trial to assess the effect of the closed-loop system on hypoglycemia.”

Other limitations included the brief trial duration, and the fact that the trial population “was not fully representative of the general population.”

  1. Be aware that in a randomized trial of children with type 1 diabetes a closed-loop insulin delivery increased time in glucose target range by an average of 2.6 hours compared to sensor-augmented insulin pump.

  2. Note that 51% of children in the closed-loop insulin delivery system group achieved glycated hemoglobin levels of less than 7% versus 18% of those in the control group.

Peggy Peck, Editor-in-Chief, BreakingMED™

The trial was supported by Tandem Diabetes Care and the National Institute of Diabetes and Digestive and Kidney Diseases. Tandem Diabetes Care provided the experimental closed-loop systems used in the trial, system-related supplies including the Dexcom continuous glucose monitor and the Roche glucometer, and technical expertise.

Breton reported receiving consulting fees from Air Liquide, grant support, paid to the University of Virginia, consulting fees, and conference attendance fees from Dexcom, grant support, paid to the University of Virginia, and conference attendance fees from Tandem Diabetes Care, and holding pending patent 61/500.545 PCT/US2012/043910 on DiAs (a scalable system for monitoring and control of blood glucose fluctuation; licensed to Dexcom), patent 10420489 on a system coordinator and modular architecture for open-loop control of diabetes (licensed to Dexcom), pending patent 62/173.080 PCT/US2016/036729 on continuous glucose monitoring (CGM)–based fault detection and mitigation of insulin delivery and monitoring systems via metabolic state (licensed to Dexcom), and patent 9750438 on CGM-based prevention of hypoglycemia through hypoglycemia rise assessment and smooth reduction of insulin (licensed to Dexcom).

Cat ID: 138

Topic ID: 85,138,730,12,187,307,138,192,669,918,925