Clinical Pearls & Morning Reports
Published October 30, 2019
Brown et al. conducted the International Diabetes Closed Loop (iDCL) trial, which compared a closed-loop system to a sensor-augmented pump for insulin delivery in patients with type 1 diabetes. Read the Original Article here.
Q: Is a “closed-loop system” considered an “artificial pancreas”?
A: Despite advances in care, attaining good glycemic outcomes in patients with type 1 diabetes remains challenging; the targets set by the American Diabetes Association are met in only a minority of patients. The use of a closed-loop system (also referred to as an “artificial pancreas”) that automates aspects of insulin delivery offers the potential to attain the desired glycemic outcomes. Meta-analyses have suggested that closed-loop systems are effective.
Q: What are some of the features of the closed-loop system used in the iDCL trial?
A: Currently, one closed-loop system is in commercial use in the United States, but randomized trials are needed to assess its efficacy and safety. This closed-loop system uses an algorithm with a dedicated hypoglycemia safety module, automated correction boluses, and overnight intensification of basal insulin delivery designed to consistently target near-normal glycemia each morning.
A: The primary outcome of the trial was the percentage of time that the glucose level, as measured by the continuous glucose monitor, was in the target range of 70 to 180 mg per deciliter (3.9 to 10.0 mmol per liter) over a 6-month period. In the trial, the percentage of time that glucose was in the target range was 11 percentage points higher among patients with the closed-loop system than among those with a sensor-augmented pump, an advantage that amounted to 2.6 hours per day (10 percentage points [2.4 hours per day] less time in hyperglycemia and 0.88 percentage points [13 minutes per day] less time in hypoglycemia). All five secondary outcomes included in the hierarchical analysis plan (percentage of time that the glucose level was >180 mg per deciliter, mean glucose level, glycated hemoglobin level, percentage of time that the glucose level was <70 mg per deciliter, and percentage of time that the glucose level was <54 mg per deciliter) met the prespecified criterion for significance in favor of the closed-loop system. Beneficial glycemic effects associated with the closed-loop system were seen during both daytime and nighttime and were particularly prominent in the second half of the night.
A: Interpretation of the present results must be viewed in the context of the characteristics of the participants and the setting of university-based diabetes centers. In the trial, 70% of the patients were using a continuous glucose monitor and 79% were using an insulin pump at the time of enrollment, percentages that are substantially higher than the reported usage in the general population of patients with type 1 diabetes. These data may reflect an interest in and willingness to use a closed-loop system among patients who were already using devices as part of diabetes management. However, the results appeared to be similar in patients who were not using a pump or a continuous glucose monitor before the trial.