Activating the exercise mode ahead of physical activity can help prevent glucose drops in individuals with type 1 diabetes mellitus (T1DM) using automated insulin delivery systems, according to findings published in Diabetes Care.

This three-way crossover study involved 38 adults and adolescents (mean age 30 years; mean HbA1c 7.5%) who completed a 70-minute treadmill session at 64–76% of their maximum heart rate under three conditions: exercise mode enabled 60 minutes (AF-60) or 30 minutes (AF-30) before activity, and standard automated mode (Auto).

Both AF-60 and AF-30 significantly reduced insulin delivery in the hour preceding and during exercise (P < 0.001) and lessened glucose decline compared with Auto (−44 mg/dL and −36 mg/dL vs −57 mg/dL; P = 0.02 and 0.01, respectively). The proportion of participants developing hypoglycemia did not differ significantly among conditions, and post-exercise glucose and insulin delivery were similar across groups.

The findings suggest that activating exercise mode 30–60 minutes before activity helps maintain glucose stability without raising hypoglycemia risk. Additional strategies, such as earlier activation or carbohydrate intake, may further reduce post-exercise glycemic fluctuations.