Study shows marathoners with type 1 diabetes can finish safely using glucose monitors

A small study presented at the European Association for the Study of Diabetes meeting in Milan found that people with type 1 diabetes can safely complete a marathon using continuous glucose monitors, achieving finish times similar to runners without the condition. The observational study of 20 amateur runners, including 10 with type 1 diabetes, took place during the 2025 Poznań Marathon. All diabetic participants finished the race, with a median completion time of 228 minutes versus 248 minutes for controls. One runner experienced two hypoglycemic episodes but completed the race, having started with glucose below the target range. Researchers noted that continuous glucose monitor accuracy was reduced during the marathon, with readings differing from glucometer measurements by roughly 37-43%. They recommend runners verify glucose levels with a glucometer during long endurance events, especially when sensor readings don't match physical feelings, and emphasize consulting doctors for individualized insulin and carbohydrate plans.