Background: Exercise-induced hypoglycemia is a major barrier for physical activity practice. Compared to conventional insulin therapy, closed-loop (CL) insulin delivery reduces hypoglycemic risk during post-absorptive exercise but has not been studied during postprandial exercise.

Methods: Randomized crossover trial comparing 3 strategies for a postprandial (PP) exercise (90 min after breakfast) at 60% of VO2peak for 60min: 1) Unannounced exercise (Unann); 2) Announced exercise with reduced insulin bolus (Ann+RB): increased glucose target combined with a 33% meal bolus reduction); 3) Announced exercise with full bolus (Ann+FB): increased glucose target combined with usual meal bolus in 37 adults with type 1 diabetes.

Results: Median percentage time spent in hypoglycemia (<70 mg/dl) was reduced with Ann+RB compared to Unann (Primary outcome; 0[0-0]% vs. 0[0-26]%; p<0.05). The drop in plasma glucose during exercise was smaller with Ann+RB (-5.5 ± 50.5 than with Ann+FB (-46.8 ± 52.2) and Unann (-43.2 ± 48.6) strategies (p <0.05). Accordingly, hypoglycemic events were reduced with Ann+RB (n=2) compared to Ann+FB (n=3) and Unann (n=9). However, Ann+BR strategy was associated with increased time in hyperglycemia (> 250mg/dl).

Conclusion: Announcement of postprandial exercise to the closed-loop algorithm combined with meal bolus reduction reduced hypoglycemic risk, yet at the expense of mild increase in hyperglycemia.


S. Tagougui: None. N. Taleb: None. C. Suppere: None. I. Boukabous: None. V. Messier: Other Relationship; Self; Eli Lilly and Company. R. Rabasa-Lhoret: Advisory Panel; Self; AstraZeneca, Boehringer Ingelheim International GmbH, Janssen Pharmaceuticals, Inc., Lilly Diabetes, Merck & Co., Inc., Novo Nordisk A/S, Sanofi. Research Support; Self; AstraZeneca, Janssen Pharmaceuticals, Inc., Novo Nordisk A/S.

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