Insulin on Board (IOB)

Insulin on Board (IOB), also called “active insulin,” is the amount of insulin that is still working in the body after a bolus dose and further lowers blood sugar. Proper consideration of IOB is crucial to avoid insulin stacking and subsequent severe hypoglycemia.

Why IOB is important

Insulin does not work immediately, but usually lasts 3-5 hours. If a new bolus is given within this time, the effect will be cumulative. Modern insulin pumps and bolus calculators automatically calculate IOB and subtract the amount of insulin that is still active from a new bolus.

Practical significance

  • Avoiding insulin stacking and severe hypoglycemia
  • Safe correction of elevated blood sugar levels
  • Better planning for exercise, meals and at night
  • Automatic calculation in modern insulin pumps and CGM apps

Influencing factors

The effect of IOB is influenced by:

  • Type of insulin (fast-acting analogues have a shorter duration of action)
  • Physical activity (sport increases the effect)
  • Individual absorption speed

Further information:
→ Diabetes mellitus – knowledge and overview
→ Why hyporest
→ Bolus calculation

Sources

  1. German Diabetes Society (DDG). S3 guideline “Insulin therapy”. As of 2025. Available at: www.deutsche-diabetes-gesellschaft.de/leitlinien.
  2. American Diabetes Association. Standards of Medical Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1). Available at: diabetesjournals.org.
  3. Robert Koch Institute (RKI). Federal health reporting – diabetes mellitus in Germany. Berlin 2024.
  4. 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

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