Insulin Correction Factor (ICF/ISF)
Estimates how much 1 unit of rapid-acting insulin will lower blood glucose. Calculated using 'Rule of 1700' (mmol/L) or 'Rule of 1800' (mg/dL) divided by Total Daily Dose (TDD). Used for correction bolus dosing in type 1 and type 2 diabetes.
Score interpretation
ISF <0.5 mmol/L/unit — high TDD; each unit has small effect
→ Use small correction doses; risk of hypoglycaemia with overcorrection; frequent glucose monitoring; ensure carbohydrate ratio and basal rate are also optimised; endocrinology/diabetes specialist review recommended
ISF 0.5–3.0 mmol/L/unit — typical sensitivity range
→ Calculate correction dose = (current BG − target BG) ÷ ISF; administer calculated correction bolus; recheck glucose in 2 hours; do not stack correction doses; document and review HbA1c regularly
ISF >3 mmol/L/unit — very sensitive; low TDD
→ Use very small correction doses (0.5 units); high hypoglycaemia risk; consider insulin pen with half-unit increments; close glucose monitoring; DAFNE or DESMOND education programme
Interpretation bands for the Insulin Sensitivity Factor. Apply clinical judgement and local guidance.
References
- Walsh J et al. Using Insulin: Everything You Need for Success with Insulin. Torrey Pines Press. 2003.
Related
Curated clinical cross-links plus same-class fallbacks.
- Insulin (IV Infusion — ICU Glucose Control) · Insulin — ICU Glucose Management
- Insulin Aspart · Rapid-Acting Insulin Analogue (Bolus)
- Tirzepatide · Dual GIP/GLP-1 Receptor Agonist — Type 2 Diabetes / Obesity
- Dopamine (ICU — Vasopressor/Inotrope) · Catecholamine (Dose-Dependent Vasopressor/Inotrope)
- Sodium Chloride 3% (Hypertonic Saline) · Hypertonic Electrolyte Solution — ICP/Hyponatraemia Management
- Hydroxocobalamin (High-Dose — Cyanide Antidote) · Cyanide Antidote (Vitamin B12 Precursor at High Dose)
- Diabetic Ketoacidosis (DKA) · JBDS 2013 / Joint British Diabetes Societies; NICE NG17
- Adult Hypoglycaemia (Treated Diabetes) · JBDS-IP (2023): Hospital Management of Hypoglycaemia
- Adrenal Crisis · Society for Endocrinology Emergency Guidance (2024)
- Type 2 Diabetes Management · NICE NG28 2022
- Hyperthyroidism Management · BTA / ETA 2018
- Adrenal Insufficiency · Society of Endocrinology / ESE 2016
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.