The Somogyi effect (also called rebound hyperglycemia) describes a sharp increase in blood sugar in the morning after a night of hypoglycemia. The body reacts to hypoglycemia with an excessive release of counter-regulatory hormones and causes blood sugar to overshoot.
Causes
The Somogyi effect usually arises from a mismatch between insulin intake and glucose requirements at night:
- Evening basal insulin dose too high
- Too little carbohydrate intake at dinner
- Late physical activity without insulin adjustment
- Drinking alcohol in the evening
Differential diagnosis: Somogyi effect vs. Dawn phenomenon
| criterion | Somogyi effect | Dawn phenomenon |
|---|---|---|
| Cause | Nocturnal hypoglycemia with counterregulation | Hormonal surge in the morning |
| Blood sugar at 3 a.m | greatly reduced (< 70 mg/dl) | normal or slightly increased |
| blood sugar in the morning | greatly increased | increased |
Symptoms
In addition to the increased morning value, non-specific signs often occur:
- Night sweats and restlessness
- Nightmares
- Morning headache
- Marked daytime tiredness
Therapy and prevention
The most important measures are:
- Reducing the evening basal insulin dose
- Carbohydrate-rich late meal with protein and fat
- With an insulin pump: lowering the nocturnal basal rate
- Regular nightly blood sugar measurements for control
Further information:
→ Diabetes mellitus – knowledge and overview
→ Why hyporest
→ Dawn phenomenon
Sources
- German Diabetes Society (DDG). S3 guideline “Diabetes mellitus type 1 and type 2”. 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
