Small study shows marathon running is safe with type 1 diabetes using CGM

A small study presented at the European Association for the Study of Diabetes meeting in Milan shows people with type 1 diabetes can safely complete a marathon using continuous glucose monitors, achieving finishing times similar to runners without the condition. The observational study of 20 amateur runners in the 2025 Poznań Marathon found no significant performance difference, with completion times of 228 minutes for diabetic participants versus 248 minutes for controls. One diabetic runner experienced two hypoglycemic episodes but finished the race. Researchers noted CGM accuracy was reduced during the marathon, with readings differing from glucometer measurements by up to 43 percent. They advise runners to verify glucose levels with a glucometer during long events, especially when sensor readings conflict with physical symptoms.