Insulin Sensitivity Calculator

ISF = Rule ÷ TDD · ICR = Rule ÷ TDD

Diabetes Management

Patient Data & Rules

TDD (units/day)

Body weight (kg) – optional

TDD = basal + bolus insulin over 24 h. Weight‑based estimate ~0.55 units/kg .

Insulin Sensitivity Factor (ISF) Rule

ISF = 1800 ÷ TDD (mg/dL per unit) . Higher rule = more sensitive.

Insulin‑to‑Carb Ratio (ICR) Rule

ICR = 500 ÷ TDD (grams carb per unit) . 500 for rapid‑acting, 450 for regular.

mg/dLmmol/L

For mmol/L, ISF values are divided by 18.

Insulin Sensitivity Factor

Enter TDD

Insulin‑to‑Carb Ratio

Enter TDD

ISF (rapid)1800 / TDD

ISF (regular)1500 / TDD

ICR500 / TDD

Initial TDD0.55 × weight (kg)

SensitiveISF >50

AverageISF 30–50

ResistantISF <30

Insulin sensitivity is affected by age, weight, physical activity, illness, and medications. Always adjust based on glucose patterns.