A Closed-Loop System in Children with Type 1 Diabetes

Published
Posted by Carla Rothaus

In the trial by Breton et al., how did the closed-loop system compare with a sensor-augmented insulin pump with respect to the primary outcome?

Breton et al. conducted a randomized trial involving children 6 to 13 years of age with type 1 diabetes that compared glycemic control using a closed-loop system for insulin delivery with that of a sensor-augmented insulin pump. Read the NEJM Original Article here.

Clinical Pearls

Q: How many children in the U.S. with type 1 diabetes attain a glycated hemoglobin level of less than 7%?

A: The glycemic target of a glycated hemoglobin level of less than 7% (as recommended by the American Diabetes Association) is attained by less than 20% of children with type 1 diabetes. The use of a closed-loop system that automates insulin delivery in a glucose-responsive manner (also referred to as an automated insulin delivery system or artificial pancreas) has the potential to improve glycemic outcomes and quality of life in these children.

Q: Has the closed-loop system been evaluated previously in randomized trials in children?

A: A single closed-loop system for insulin delivery was approved in the United States for children 6 to 13 years of age; however, to date, published studies on its efficacy and safety have been limited to single-group studies with no randomization.


Morning Report Questions

Q: In the trial by Breton et al., how did the closed-loop system compare with a sensor-augmented insulin pump (control group) with respect to the primary outcome?

A: The primary outcome of the trial was the percentage of time that the glucose level was in the target range of 70 to 180 mg per deciliter (3.9 to 10.0 mmol per liter), as measured by continuous glucose monitoring. The mean (±SD) percentage of time that the glucose level was in the target range of 70 to 180 mg per deciliter increased from 53±17% at baseline to 67±10% (the mean over 16 weeks of treatment) in the closed-loop group and from 51±16% to 55±13% in the control group (mean adjusted difference, 11 percentage points [equivalent to 2.6 hours per day]; 95% confidence interval (CI), 7 to 14; P<0.001). The percentage of time that the glucose level was in the target range consistently favored the closed-loop group over the control group across a broad range of baseline characteristics. The treatment effect was evident in the first month and appeared to be consistent over 4 months. 

Q: What were some of the secondary outcome results in the trial by Breton et al.?

A: The beneficial effect of the closed-loop system was more prominent overnight than during the day. Treatment effects that favored the closed-loop group over the control group were also observed for the percentage of time with the glucose value above 180 mg per deciliter and for the mean glucose level. The mean adjusted between-group difference in the glycated hemoglobin level at 16 weeks was −0.4 percentage points (95% CI, −0.9 to 0.1; P=0.08), which did not meet the threshold for statistical significance. In both groups, the median percentage of time with the glucose level below 70 mg per deciliter was low (1.6% and 1.8% in the closed-loop group and the control group, respectively). Severe hypoglycemia or diabetic ketoacidosis did not occur in either treatment group.

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