What You Eat Before Exercise May Help Steady Blood Sugar in Type 1 Diabetes

Researchers asked 12 adults with Type 1 diabetes to follow three different eating patterns for a week at a time. All three diets had the same number of calories but different mixtures of carbohydrates, fat, and protein. The high-carbohydrate diet was 48% carbs, 33% fat, and 19% protein. The first low-carbohydrate option was 19% carbs, 62% fat, and 19% protein. The second low-carbohydrate option was 19% carbs, 57% fat, and 24% protein.

After each week of eating, participants rode a stationary bike for 45 minutes while fasting. Researchers measured blood sugar levels and fat levels throughout exercise and tracked how much carbohydrate versus fat their bodies burned.

During exercise on the low-carbohydrate, high-fat diet, participants burned significantly more fat and less carbohydrate compared to the high-carbohydrate diet. Both low-carbohydrate diets were associated with higher blood sugar stability—participants spent more time in their target blood sugar range and less time in high blood sugar territory.

On the high-carbohydrate diet, participants spent about 56% of the exercise period in target range and 44% in high blood sugar. On the low-carbohydrate diets, time in target range jumped to 87% and 95%, while high blood sugar episodes dropped to about 13% and 5% respectively.

These findings suggest that the foods you eat in the days before exercise may influence how your body regulates blood sugar during physical activity. When your body is adapted to using fat as fuel—which happens when carbohydrates are restricted—it may handle exercise differently than when it expects carbohydrate to be readily available.

However, this was a small study involving just 12 people. Larger studies are needed to confirm whether these patterns hold true across different populations and individual circumstances. Additionally, everyone's body responds differently to dietary changes, so the 'best' approach will vary from person to person.

If you're interested in exploring how diet affects your exercise performance and blood sugar management, talk with your healthcare team. They can help you understand what approach might work best for your individual situation and ensure any dietary changes align with your insulin regimen and overall diabetes management plan.

This research adds to growing evidence about the connection between nutrition and blood sugar control during activity, but it's one study among many. Your own experience and feedback from your care team should always guide your decisions.

Source: Nutrients. Evidence type: PubMed indexed literature. 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.