Running a Race With Type 1 Diabetes: What the Data Shows

What Was Studied — and Why It Matters

For people with type 1 diabetes (T1D), signing up for a running race raises real questions: How will my blood sugar behave? Should I change my insulin? Could I go dangerously low mid-race? Researchers in Germany set out to answer exactly these questions by tracking 12 adults with T1D alongside 12 people without diabetes during an actual running competition.

How the Study Worked

All 24 participants wore a continuous glucose monitor — the FreeStyle Libre — for 24 hours before the race, during the event, and 24 hours afterward. They also logged everything they ate and every insulin dose they took. This gave researchers a detailed picture of how blood sugar moved in real-world race conditions, not just a lab treadmill.

What the Researchers Found

Blood Sugar Control Was Harder for T1D Runners

Compared to healthy participants, people with T1D spent significantly less time with their glucose in a healthy range:

• Time in Range: T1D runners averaged 63% — healthy runners averaged 89%
• Time above target: T1D runners spent measurable time in elevated glucose zones; healthy runners spent essentially zero time there
• Greater swings overall: Blood sugar variability — the up-and-down fluctuations — was significantly higher in the T1D group

Cutting Basal Insulin Made a Real Difference

Here's the encouraging part: the T1D participants reduced their long-acting (basal) insulin doses significantly around the competition, and it worked. On the day before the race, doses were cut by about 50% on average. On race day itself, doses were reduced by roughly 32%. These reductions appeared to prevent blood sugar from crashing dangerously low during exercise — a serious risk for anyone with T1D who is physically active.

What This Means for You

If you have type 1 diabetes and want to participate in endurance events like running races, this research backs up what many diabetes care teams already recommend: proactively reducing your basal insulin in the days around intense exercise can help stabilize your glucose without triggering dangerous highs. However, blood sugar control will still be more challenging than it is for people without diabetes, so preparation is everything.

That preparation includes having reliable supplies on hand. MDS Diabetes carries continuous glucose monitoring accessories, insulin supplies, and other essentials so active patients can focus on their performance — not on whether they have what they need.

Talk to Your Care Team Before Race Day

Everyone's insulin needs are different. The reductions in this study were supervised and monitored closely. Before adjusting your own doses for a race or long workout, work with your endocrinologist or diabetes educator to build a plan that fits your specific regimen and fitness level.

Bottom Line

Adults with type 1 diabetes can participate in running competitions, but blood sugar management requires extra planning. Reducing basal insulin by up to 50% before and during a race helped prevent low blood sugar in this study. Wearing a continuous glucose monitor throughout the event gave participants — and researchers — the real-time data needed to stay safe. With the right strategy and supplies, the finish line is absolutely within reach.