Insulin Resistance Calculator (HOMA-IR)
The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) is a widely used clinical and research tool for estimating insulin resistance from simple fasting blood test results. Developed by Matthews and colleagues in 1985 at the University of Oxford, it provides a practical alternative to the gold-standard euglycaemic clamp test. HOMA-IR is calculated from fasting plasma insulin (in mIU/L) and fasting plasma glucose (in mg/dL). Scores below 1.0 suggest normal insulin sensitivity; scores above 2.5-3.0 suggest insulin resistance. This tool is educational - you need actual fasting blood test results to use it, and interpretation should be discussed with your healthcare provider.
HOMA-IR formula (Matthews et al. 1985)
HOMA-IR = (Fasting Insulin mIU/L x Fasting Glucose mg/dL) / 405
Alternatively: (Insulin mIU/L x Glucose mmol/L) / 22.5
Thresholds: Normal below 1.0; Insulin resistant above 2.5-3.0 (population-dependent)
Insulin resistance: frequently asked questions
What is HOMA-IR?
The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) was developed by Matthews et al. in 1985. It estimates insulin resistance from fasting blood glucose and fasting insulin levels. The formula HOMA-IR = (Fasting Insulin x Fasting Glucose) / 405 (when glucose is in mg/dL) or / 22.5 (when glucose is in mmol/L) provides a simple surrogate for the more complex euglycaemic-hyperinsulinaemic clamp test.
What is a normal HOMA-IR score?
Normal HOMA-IR in healthy lean adults is generally below 1.0. HOMA-IR above 1.9 is often used as a threshold for insulin resistance in research; some studies use 2.5 or 3.0 in clinical settings. Population averages vary significantly by ethnicity, age, and BMI. A score above 2.5-3.0 is associated with increased risk of metabolic syndrome, type 2 diabetes, and cardiovascular disease in most populations.
What causes insulin resistance?
Insulin resistance occurs when cells do not respond normally to insulin, requiring the pancreas to produce more insulin to maintain blood glucose control. Primary causes include excess body fat (especially visceral fat), physical inactivity, poor diet (high refined carbohydrates and saturated fat), sleep deprivation, and chronic stress. Genetic factors also play a role. Insulin resistance is the primary pathological mechanism behind type 2 diabetes, metabolic syndrome, and PCOS.
Can insulin resistance be reversed?
Yes. Lifestyle interventions can dramatically improve insulin sensitivity. Regular aerobic and resistance exercise improves glucose uptake by skeletal muscle independently of insulin. Weight loss (even 5-10% of body weight) significantly reduces visceral fat and improves HOMA-IR. A diet lower in refined carbohydrates and higher in fibre, protein, and healthy fats helps. The NIH-funded Diabetes Prevention Program showed that lifestyle intervention reduced type 2 diabetes risk by 58% in people with prediabetes.
How is fasting insulin measured?
Fasting insulin requires a blood test after a minimum 8-hour fast. A normal fasting insulin level is typically 2-20 mIU/L (or mcU/mL), though some labs use different units. Fasting insulin testing is not included in standard metabolic panels and must be specifically ordered. Elevated fasting insulin (hyperinsulinaemia) before glucose levels rise is an early marker of insulin resistance. Always discuss insulin testing with your healthcare provider.
Official sources
- NIH National Library of Medicine: HOMA-IR - Assessment of Insulin Resistance (Matthews et al. 1985).
- CDC: National Diabetes Prevention Program.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.