Excellent Glycemic Control Maintained by Open-Source Hybrid Closed-Loop AndroidAPS During and After Sustained Physical Activity

Objective: Officially licensed hybrid closed-loop systems are not currently available worldwide; therefore, open-source systems have become increasingly popular. Our aim was to assess the safety, feasibility, and efficacy of an open-source hybrid closed-loop system (AndroidAPS) versus SmartGuard((R)) technology for day-and-night glucose control in children under extreme sports conditions. Research Design and Methods: Twenty-two children (16 girls, 6-15 years of age, median HbA1c 569mmol/mol) were enrolled in this pivotal winter sports camp study. The participants were divided into two groups using either the AndroidAPS or SmartGuard technology. Physical exertion was represented by all-day alpine skiing. The primary endpoints were mean glucose level, time below the threshold of 3.9mmol/L, and time within the target range of 3.9 to 10mmol/L. Results: The children using the AndroidAPS had significantly lower mean glycemia levels (7.2 +/- 2.7 vs. 7.7 +/- 2.8mmol/L; 129.6 +/- 49 vs. 138.6 +/- 50mg/dL, P<0.042) than the children using the SmartGuard. The proportion of time below the target (median 5.0%+/- 2.5% vs. 3.0%+/- 2.3%, P=0.6) and in the target zone (63%+/- 9.5% vs. 63%+/- 18%, P=0.5) did not significantly differ. The AndroidAPS group experienced more frequent malfunctions of the cannula set (median 0.8 +/- 0.4 vs. 0.2 +/- 0.4, P=0.02), which could have affected the results. No significant difference was found in the amount of carbohydrates consumed for the prevention and treatment of hypoglycemia [median 40 +/- 23 vs. 25 +/- 29g/(patient 3 days)]. No episodes of severe hypoglycemia or other serious adverse events were noted. Conclusions: This pilot study showed that the AndroidAPS system was a safe and feasible alternative to the SmartGuard Technology.