HOMA-IR Calculator: Estimate Insulin Resistance From Fasting Glucose and Insulin

The HOMA-IR calculator above turns two numbers from a fasting blood test (glucose and insulin) into an estimate of insulin resistance. It also shows QUICKI, a related index. Everything runs in your browser.

What HOMA-IR measures

HOMA stands for Homeostatic Model Assessment. It was introduced by David Matthews and colleagues in 1985 as a way to estimate insulin resistance and beta-cell function from a single fasting sample, instead of the hours-long clamp studies used in research labs.

The idea is simple. After an overnight fast, your pancreas releases just enough insulin to hold your blood glucose steady. If your body responds well to insulin, a little insulin is enough. If it responds poorly, your pancreas has to release more insulin to keep glucose in range, so fasting insulin, glucose, or both creep up.

The formula

Glucose unit	HOMA-IR formula
mmol/L	fasting insulin (µIU/mL) × fasting glucose (mmol/L) ÷ 22.5
mg/dL	fasting insulin (µIU/mL) × fasting glucose (mg/dL) ÷ 405

Insulin is often reported as µIU/mL (the same as mU/L). If your lab reports pmol/L, divide by 6 to convert; the calculator does this for you.

Worked example. Fasting glucose 92 mg/dL (5.1 mmol/L) and fasting insulin 8 µIU/mL give 8 × 5.1 ÷ 22.5 ≈ 1.8.

QUICKI, the Quantitative Insulin Sensitivity Check Index, uses the same two numbers on a logarithmic scale: 1 ÷ (log insulin + log glucose in mg/dL). Lower QUICKI values mean lower insulin sensitivity.

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How to read your number

• About 1: the level the model was built around for young, lean, healthy adults.
• Under about 2: common in healthy adults.
• About 2 to 3: the zone where many studies start to flag insulin resistance.
• Above 3: above most published cut-offs.

There is no single official threshold. Cut-offs published in research differ with age, ethnicity, body weight and, above all, the insulin assay a lab uses, because insulin tests are not standardized the way glucose tests are. Treat the bands as orientation, not a verdict.

When HOMA-IR is not reliable

• Non-fasting samples. A meal raises both glucose and insulin and breaks the model.
• Insulin treatment. Injected insulin is indistinguishable from your own in the blood test.
• Very low insulin production, as in type 1 diabetes or advanced type 2 diabetes.
• One sample. Insulin is released in pulses, so a single measurement varies; research studies often average several samples.
• Comparing labs. A value from one lab is not directly comparable with a value from another.

The original formula is sometimes called HOMA1. An updated computer model, HOMA2 (Levy, Matthews and Hermans, 1998), accounts for more physiology and gives somewhat different numbers, so check which version a study or report uses before comparing.

HOMA-IR is not a diabetes test

Diabetes and prediabetes are diagnosed with established tests. In the American Diabetes Association’s criteria, fasting glucose of 100 to 125 mg/dL, or HbA1c of 5.7 to 6.4%, indicates prediabetes; fasting glucose of 126 mg/dL or more, or HbA1c of 6.5% or more, meets the threshold for diabetes when confirmed. HOMA-IR can add context, because insulin resistance often comes years before glucose rises, but it does not replace those tests.

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What tends to move it

HOMA-IR usually improves when insulin sensitivity improves: losing excess weight (especially around the waist), regular physical activity, adequate sleep, and a diet lower in refined carbohydrates and added sugars. Trials of carbohydrate-restricted eating often report lower fasting insulin and HOMA-IR, largely alongside weight loss; other approaches that produce similar weight loss can show similar changes. Medications and health conditions matter too, so any plan is best made with your doctor.

Sources

• Matthews DR, Hosker JP, Rudenski AS, et al. Homeostasis model assessment: insulin resistance and β-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia 1985;28:412–419. doi:10.1007/BF00280883
• Katz A, Nambi SS, Mather K, et al. Quantitative insulin sensitivity check index. J Clin Endocrinol Metab 2000;85:2402–2410. doi:10.1210/jcem.85.7.6661
• Levy JC, Matthews DR, Hermans MP. Correct homeostasis model assessment (HOMA) evaluation uses the computer program. Diabetes Care 1998;21:2191–2192. doi:10.2337/diacare.21.12.2191
• American Diabetes Association. Standards of Care in Diabetes: diagnosis and classification. professional.diabetes.org

P.S. A few readers have asked which books & cookbooks we actually reach for — it's What The Fat? / What The Fast? Book Series; take a look here if you want the current details.