Lipohypertrophy, often referred to in everyday life as an “injection mound”, is a thickening of the subcutaneous fatty tissue in places where insulin is often injected or an infusion set is placed. The altered tissue leads to delayed and irregular absorption of insulin and is one of the most common causes of unpredictable blood sugar fluctuations.
Causes
Lipohypertrophy results from repeated mechanical stimulation and the local fat-promoting effect of insulin. The main causes are:
- Use the same puncture site over and over again
- Missing or too short rotation of the injection sites
- Reuse pen needles
- The puncture angle is too flat or the needles are too short
Follow
The changed tissue absorbs insulin more poorly and irregularly. This leads to:
- Delayed onset of insulin action
- Strong blood sugar fluctuations (high values after injections, late hypoglycemia)
- Often higher insulin doses, although the insulin “fizzles out” in the hill
- Worse HbA1c despite high doses
Diagnostics
Detection is done by:
- Regular inspection and palpation of injection sites
- Palpable hardening or visible protrusions
Prevention and treatment
The most important measure is consistent rotation of the injection sites. Further recommendations:
- Avoid affected areas for at least 4-8 weeks until the tissue has receded
- Systematic rotation plans (e.g. clock pattern on the stomach)
- Always use new pen needles
- For insulin pumps: Change and rotate the infusion set every 2-3 days
Further information:
→ Diabetes mellitus – knowledge and overview
→ Why hyporest
→ Insulin pump therapy (CSII)
Sources
- German Diabetes Society (DDG). S3 guideline “Insulin therapy”. 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
