How Exercise Affects Blood Sugar in Type 1 Diabetes: New Research on CGM Data

For people living with type 1 diabetes, physical activity affects blood sugar in complex ways. While many know that exercise can lower glucose, the timing and magnitude of these effects vary from person to person. Researchers wanted to learn whether combining continuous glucose monitor (CGM) data with exercise information could reveal meaningful patterns that help individuals make better decisions about when and how to exercise.

This proof-of-concept study followed 17 adults with type 1 diabetes over 10 weeks. Participants had relatively low exercise levels at the start and received support through a digital app that included exercise videos, text-based coaching, a self-monitoring diary, and monthly personalized feedback sessions. During these sessions, researchers shared insights based on CGM readings alongside other data like mood and sleep patterns.

The research team focused their analysis on the evening and overnight hours (6 p.m. to 6 a.m.) to capture both immediate and delayed glucose effects from daytime exercise. They measured outcomes including average glucose levels, time spent in target range (70–180 mg/dL), time in high blood sugar (≥250 mg/dL), and time in low blood sugar (≤70 mg/dL).

When comparing exercise days to non-exercise days, adults in the study had lower average blood glucose levels on days they exercised. The difference was modest—roughly 3 mg/dL lower—but consistent. The research also examined whether exercise reduced the odds of high or low blood sugar episodes, adjusting for factors like age, diabetes duration, weight, and HbA1c.

This small study suggests that tracking exercise alongside CGM data may help reveal how your individual body responds to physical activity. By reviewing this combined information with support from a healthcare provider or diabetes educator, you might identify patterns specific to your own glucose management. The research was designed for people with low baseline exercise levels, so these findings may be most relevant to those beginning or returning to regular activity.

More research with larger groups and longer follow-up periods would help confirm these patterns and determine whether this personalized feedback approach leads to sustained behavior change and improved long-term glucose control.

Source: Human factors in healthcare. 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.