Insulin sensitivity factor (ISF)
Also called correction factor, CF.
The insulin sensitivity factor, also called the correction factor, is how far one unit of insulin is expected to lower glucose, in mg/dL or mmol/L. A bolus calculator uses it for the correction part of a bolus, together with a target glucose. A care team sets it, and ADA guidance says to adjust it when corrections do not bring glucose into range. (OpenAPS documentation; ADA Standards of Care 2026, section 9; ADA Standards of Care 2026, section 7)
Formula
Correction insulin (units) = (current glucose − target glucose) ÷ ISF
Worked example
Arithmetic only: glucose 220 mg/dL, target 120 mg/dL, ISF 50 mg/dL per unit: (220 − 120) ÷ 50 = 2 units. In mmol/L: (12.2 − 6.7) ÷ 2.8 = 2 units.
Related terms
Sources, quoted
- OpenAPS documentation: “ISF - insulin sensitivity factor - the expected decrease in BG as a result of one unit of insulin.”
- ADA Standards of Care 2026, section 9: “Correction insulin: adjust ISF and/or target glucose if correction does not consistently bring glucose into range.”
- ADA Standards of Care 2026, section 9: “Mealtime and correction: URAA or RAA by bolus based on ICR and/or ISF and target glucose”
- ADA Standards of Care 2026, section 7: “Health care professional input and education can be helpful for setting the initial dosing calculations with ongoing follow-up for adjustments as needed.”
Every quote above is checked against its source page before each update of this site; last checked 2026-10-06. The worked example is our own arithmetic. This page explains a term; it is not advice for a person's treatment.