Hybrid Closed-Loop Disconnection Reduces the Risk of Hypoglycemia in Active Children and Adolescents with Type 1 Diabetes: A Randomized Controlled Pilot Study

Introduction: Optimizing hybrid closed-loop (HCL) performance around exercise in children with type 1 diabetes (T1D) is challenging. Methods: In this prospective, randomized, controlled pilot study conducted during a 7-day holiday camp, participants using Medtronic MiniMed 780 G and continuous glucose monitoring (CGM) were randomized to two strategies of HCL use for physical activity (1–2 sessions/day): pump kept connected in auto-mode versus suspended and disconnected. Meal boluses before exercise were not reduced, and all participants used 90-min pre-exercise temporary glucose target 150 mg/dL. Results: Of 20, 8 and 7 participants from connected and disconnected arms were eligible for analysis. Median age was 11 (10–11) years, diabetes duration was 1.6 (0.7–6.0) years, HbA1c was 6.4 (6.05–7.3)% (46, 43–56 mmol/mol), and BMI z-score was −0.25 (−0.53–1.36). HCL exercise disconnection resulted in lower time below range <70 mg/dL [3.9 mmol/L] during camp (−2.91 ± 1.3%point difference, P = 0.0250), with no difference in time in range 70–180 mg/dL [3.9–10.0 mmol/L] (+0.3 ± 4.8%point, P = 0.1677). Conclusion: Temporary HCL disconnection for exercise significantly reduces hypoglycemia risk without compromising glucose control.