Duration of Hybrid Closed-Loop Insulin Therapy to Achieve Representative Glycemic Outcomes in Adults with Type 1 Diabetes

Closed-loop insulin therapy increases the time spent in target glucose range (70–180 mg/dL) while reducing the time spent in hypoglycemia ( 180 mg/dL) (1), and it is being progressively applied in clinical practice. Randomized clinical trials of closed-loop insulin delivery have been performed over a single day to several months, but the time required to achieve representative glucose outcomes, including control algorithm individualization and behavioral adaptation, is currently unknown. To address this issue we analyzed retrospectively data collected during closed-loop clinical trials in adults with type 1 diabetes and A1C ≥58 mmol/mol (≥7.5%) as such information may be useful in determining the optimal duration of future closed-loop studies as well as follow-up assessments under routine care conditions. We combined data collected in adults aged 21 years and older during two multinational (U.K., U.S., Austria, and Germany), randomized, day-and-night, hybrid closed-loop studies (2,3) (AP@home04 and APCam11) of 12 weeks’ duration ( N = 56, mean ± SD A1C 68 ± 7 mmol/mol \[8.4 ± 0.6%\] \[range 58–83 mmol/mol (7.5–9.7%)\], age 39 ± 10 years [range 21 to 65 years], diabetes duration 21 ± 9 years [range 6 to 49 years]). The AP@home04 study (2) utilized Dana Diabecare R insulin pump (Sooil, Seoul, South Korea) and FreeStyle Navigator II glucose sensor (Abbott Diabetes Care, Alameda, CA), while the APCam11 study (3) used a modified Medtronic 640G insulin pump and Guardian 3 glucose sensor (Medtronic, Northridge, CA). Both studies used an identical individually adapting, treat-to-target, model-predictive control algorithm residing on a smartphone. Participants were required to deliver a premeal bolus based on carbohydrate content, were not remotely monitored or supervised, …