A Randomized Crossover Pilot Study Evaluating Glucose Control During Exercise Initiated 1 or 2 h After a Meal in Adults with Type 1 Diabetes Treated with an Automated Insulin Delivery System

To assess the safety and efficacy of two exercise sessions performed 60- and 120-min postmeal with a combination of meal bolus reduction and increased glucose target to the automated insulin delivery (AID) system. A randomized crossover trial in 13 adult participants (6 females) living with type 1 diabetes using AID (A1c = 7.9% ± 0.6%, age = 53.5 ± 15.5 years, T1D duration = 29.0 ± 16.0 years) was conducted. Just before breakfast, at the time of meal bolus, the AID glucose target was increased from 6 to 9 mmol/L, and a meal bolus reduction of 33% was applied. Two 60-min exercise sessions (60% of VO₂ peak) were undertaken either 60 min (60EX) or 120 min (120EX) after a standardized breakfast, followed by a 90-min recovery period. The mean reduction in plasma glucose (PG) levels from prebreakfast to postexercise (-0.8 ± 2.4 mmol/L vs. +0.3 ± 2.3 mmol/L, P = 0.082) were similar between 60EX and 120EX. From prebreakfast to postexercise, PG times in range (3.9-10.0 mmol/L; 63.4% ± 43.1% 60EX vs. 51.9% ± 29.7% 120EX, P = 0.219) and time above range (>10.0 mmol/L; 36.3% ± 43.3% 60EX vs. 48.1% ± 29.7% 120EX, P = 0.211) did not differ between interventions. The 60EX attenuated the glucose rise between premeal to pre-exercise (+1.8 ± 2.1 mmol/L 60EX vs. +3.9 ± 2.1 mmol/L 120EX, P = 0.001). No hypoglycemic events (<3.9 mmol/L) occurred during the study. Premeal announcement combining meal bolus reduction and increased glucose target was effective and safe during 60 min of moderate-intensity aerobic exercise, whether exercise onset was 60 or 120 min following a meal. NCT04031599.