772-P: Combining Meal-Bolus Reduction and Exercise Announcement Eliminates the Risk of Hypoglycemia during Postprandial Exercise in People Living with Type 1 Diabetes Treated with Automated Insulin Delivery Systems

For people living with type 1 diabetes (PWT1D) post-prandial exercise remains a challenge for the maintenance of glycemic control even with automated insulin delivery systems (AID) . During the postprandial phase, elevated insulin levels, rapid changes in glucose levels with increased CGM lag time make it difficult for AID algorithms to mitigate the risk of hypoglycemia by solely relying on basal rate modulation. The main objective of this study was to assess the safety and efficacy of AID using a combination strategy of pre-meal exercise announcement and meal bolus reduction during exercise bouts performed 1- and 2-hours post-meal. Thirteen adults PWT1D chronically treated with AID (6 females; A1c = 7.9 ± 0.6%; Age= 53,5 ± 15,5 years; T1D duration= 29.0 ± 16.0 years) were included. Participants performed in a randomized crossover fashion 2 60-min exercise sessions (60% of VO2_peak) , 1 (60Ex) and 2-h (120Ex) post-meal. A standardized meal was given at 8AM with a 33% insulin bolus reduction and exercise was announced to the AID algorithm (target glucose increased from 6 to 9 mmol/L) up to the end of each exercise session. Plasma glucose was collected regularly. Plasma glucose times in range (3.9-10.0 mmol/L) and above range (>10.0 mmol/L) from exercise onset to 90-min-post-exercise, were similar between Ex60 and Ex120 (63.7 ± 41.4% Ex60 vs. 65.9 ±24.9% Ex120, p=0.3; 36.1 ± 41.6% Ex60 vs. 34.1 ± 24.9% Ex120, p=0.4, respectively) . No hypoglycemic events (<3.9 mmol/L) occurred during the study. The mean reduction in plasma glucose levels were similar during exercise in both conditions (-2.6 ± 1.4 mmol/L Ex60 vs. -3.5 ± 2.2 mmol/L Ex120, p=0.2) Conclusion: combining pre-meal exercise announcement with a meal bolus reduction of 33% was effective and safe at preventing postprandial exercise hypoglycemia in PWT1D treated with AID whether exercise was performed 1 or 2-h after a meal.