How Different Types of Exercise Affect Blood Sugar in Type 1 Diabetes

Exercise is vital for overall health in type 1 diabetes, but it remains one of the trickier variables to manage because physical activity affects blood sugar unpredictably. The same workout can produce different glucose responses on different days, and different types of exercise can create entirely different patterns.

A new study published in the Journal of Functional Morphology and Kinesiology examined how various exercise modalities affect blood sugar in real-world conditions. Researchers tracked 120 adults with type 1 diabetes through 1,568 exercise sessions using continuous glucose monitors (CGMs) and wearable sensors, capturing what actually happens to glucose levels during everyday workouts.

Aerobic activities—like running, cycling, or swimming—produced the most pronounced blood sugar effects in the study. Aerobic exercise was associated with the greatest immediate drop in glucose levels during the workout itself. It also led to the highest amount of time spent below target blood sugar range during exercise.

The risks didn't stop when the workout ended. Aerobic exercise was linked to the highest frequency of delayed low blood sugar in the hours after exercise finished. Study participants also needed rescue carbohydrates most often following aerobic sessions, suggesting that aerobic workouts demand the most careful preparation and recovery planning.

The study categorized exercise into four types: aerobic, resistance training, interval-based workouts, and mixed exercise (combining multiple modalities). Glycemic risk—the likelihood and severity of blood sugar swings—differed meaningfully across these categories.

The research measured multiple outcomes beyond just immediate glucose changes, including severe low blood sugar events, time in range, time above range, how variable glucose readings were, whether lows occurred during sleep, and how much fast-acting carbohydrate was needed. This comprehensive approach revealed that the exercise type you choose has real consequences for your blood sugar patterns and your need for intervention.

Understanding how different workouts affect your blood sugar is a first step toward safer, more confident exercise. If aerobic activity carries higher low-blood-sugar risk in this study population, that doesn't mean you should avoid it—but it does suggest you may need different preparation strategies compared to other exercise types.

Individual responses vary, and your personal patterns with your CGM may differ from the averages in this study. Tracking your own glucose trends during different workouts gives you valuable information for planning. The key insight from this research is simply that exercise type matters, and being aware of these patterns can help you make informed decisions about fuel, insulin adjustments, and monitoring before, during, and after activity.

Source: Journal of functional morphology and kinesiology. 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.