“You Don’t Know When the Sugar’s Going to Kick In” – T1D Exchange Research on Managing Diabetes During a Marathon

The American Diabetes Association (ADA) 80th Scientific Sessions began this weekend, and T1D Exchange is excited to share the research we’ve been working on with Glu community members.

The T1D Exchange outcomes research team worked with Beyond Type 1 and runners in the New York City Marathon to examine the effects and management of type 1 diabetes while engaged in long-distance endurance running. 

Exercise can be a critical component of T1D management, but it’s not without significant challenges. Managing blood sugars during a long race presents a unique set of problems that must be dealt with.

Dealing with T1D during endurance races

The study looked at 10 participants in the NYC Marathon who ran with the Beyond Type 1 team, with an average age of 33.3 years. Ninety percent of the participants used insulin pumps, and all of them used CGMs to monitor their blood sugars.

The study found that glycemic variability occurred not just during the race but afterward as well, with the ‘recovery’ period ranging between 1 day and 3-4 months after the marathon. In the 24 hours following the marathon, runners often found that their insulin needs would change as their metabolism shifted to adapt.

Participants also managed their basal rates, onboard insulin, and other variables to best plan for the long races.

“Obviously I’m not going to go for a run if I have like six units on board, but overall, it doesn’t bother me if I have a little bit of insulin on board,” said one of the runners regarding their marathon training. “I definitely, depending on my starting blood sugar, try to have a snack before.” 

Runners also reported consuming unusually large quantities of food before and during the race to help fuel their exercise and keep their blood sugars up.
This data provides initial insight into the decision-making that occurs for people with T1D who participate in endurance activities – including food preparation, planning ahead for supplies and insulin manipulation, in-the-moment management decisions, and recovery period glucose management.

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