Marathon Running with Type 1 Diabetes: New Study Shows It's Possible with the Right Tools

A research team from Poznan University of Medical Sciences and Raszeja City Hospital in Poland studied 20 amateur runners during the 2025 Poznań Marathon—a standard 42-kilometer (26-mile) race. Ten runners had type 1 diabetes with at least one year of diabetes history, and ten runners did not have diabetes.

The researchers wanted to understand what happens to blood sugar levels during a real marathon. They tracked glucose patterns, how much carbohydrate runners ate, and how accurately CGM devices measured glucose during the race. Until now, there has been limited real-world evidence on these questions during prolonged endurance exercise.

Runners with type 1 diabetes made specific adjustments to manage their insulin and blood sugar during the race. They aimed for a pre-race glucose target of 140–200 mg/dL to have a safety buffer before starting.

On race day, insulin doses were reduced: runners using multiple daily injections cut their basal insulin by 25%, while those on non-hybrid insulin pumps reduced it by 50%. Runners using hybrid closed-loop systems—pumps that automatically adjust insulin—set a target glucose of 150 mg/dL and let the system make adjustments during the race.

All runners with type 1 diabetes completed the marathon safely. Their finishing times were comparable to the finishing times of runners without diabetes, suggesting that having type 1 diabetes did not slow them down when the race was properly managed.

The results suggest that with continuous glucose monitoring and thoughtful adjustments to insulin and carbohydrate intake, marathons can be completed safely by people with type 1 diabetes.

This research was presented at the Annual Meeting of the European Association for the Study of Diabetes in September 2026. Because it was a small study of amateur runners, the findings show what's possible but do not prove that all people with type 1 diabetes can safely run marathons without individual preparation and medical guidance.

Anyone with type 1 diabetes interested in endurance exercise like marathon running should work with their healthcare team to develop a personalized plan for insulin adjustment, glucose monitoring, and carbohydrate intake.

Origin: medicalxpress.com (News report). Evidence: News report — unverified, pending corroboration. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.