Hypoglycemia during exercise is one of the most common and dangerous complications in people with diabetes who take insulin or medications containing sulfonylurea. Due to the increased glucose uptake by the muscles and the increased insulin sensitivity, blood sugar can drop sharply during or up to 24 hours after exercise.
Causes
During and after exercise, blood sugar drops due to:
- Increased glucose consumption by working muscles
- Increased insulin sensitivity up to 48 hours after exercise
- Insufficient reduction in the amount of basal or bolus insulin
- Too little carbohydrate intake before or during exercise
Risk factors
- Intense or unfamiliar endurance sports (running, cycling, swimming)
- Long sports sessions without carbohydrate intake
- Hypoglycemia unawareness disorder
- Drinking alcohol the night before
Prevention and strategies
| Load type | Recommended actions |
|---|---|
| Short intensive session (< 45 min.) | Measure blood sugar in advance, if necessary 10-15 g carbohydrate (e.g. Hyporest) |
| Endurance (moderate, > 60 min.) | Reduce basal rate by 20-50%, 15-30 g of carbohydrate every 30-45 minutes |
| After sports | Reduce basal rate for 6-12 hours, set higher target value at night |
Pay attention to night effect
The risk of severe nocturnal hypoglycemia is particularly high after intensive sessions in the afternoon or evening. A reduction in the nighttime basal rate and a carbohydrate-rich late meal help here.
Further information:
→ Diabetes mellitus – knowledge and overview
→ Why hyporest
→ Hypoglycemia
Sources
- German Diabetes Society (DDG). S3 guidelines “Diabetes and sport”. As of 2025. Available at: www.deutsche-diabetes-gesellschaft.de/leitlinien.
- American Diabetes Association. Standards of Medical Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1). Available at: diabetesjournals.org.
- Robert Koch Institute (RKI). Federal health reporting – diabetes mellitus in Germany. Berlin 2024.
- International Diabetes Federation (IDF). IDF Diabetes Atlas. 11th edition. Brussels 2025. Available at: diabetesatlas.org.
Important note:
The information in this encyclopedia article is intended solely for general and non-binding information. They do not replace medical advice, diagnosis or therapy. If you have any health questions or complaints, please always consult a doctor or qualified healthcare professional. The content was created with the greatest possible care, but errors cannot be completely ruled out.
Last updated: February 26, 2026
