What is HOMA-IR and what does my number mean?
Written and medically reviewed by Zahraa Sater, M.D., M.P.H.
Reviewed August 12, 2026 · Next review due August 12, 2028
Short answer
HOMA-IR is a number calculated from one fasting glucose and one fasting insulin, published by Matthews and colleagues in 1985 as a research model. The original paper reported a coefficient of variation of 31 percent for its insulin resistance estimate. No diabetes guideline uses HOMA-IR to diagnose anything, and no cut-off is agreed.
HOMA-IR stands for homeostasis model assessment of insulin resistance. It is not a measurement. It is a calculation that takes a single fasting glucose and a single fasting insulin and estimates, from a mathematical model, how resistant the body appears to be. Matthews and colleagues published it in Diabetologia in 1985 to compare groups in research, and that is still where it belongs.
How HOMA-IR is calculated
The original HOMA-IR multiplies fasting insulin in microunits per millilitre by fasting glucose in millimoles per litre and divides by 22.5. Laboratories in the United States, where glucose is reported in mg/dL, divide by 405 instead. Both versions rest on one blood draw. Nothing in the calculation looks at what happens after food, at muscle mass, at liver fat or at how well the pancreas responds to a challenge.
Why the number moves so much
The authors of the original paper were direct about the limits of their own model. They reported coefficients of variation of 31 percent for the insulin resistance estimate and 32 percent for the beta cell estimate, and wrote that this low precision "limits its use". A value that can swing by roughly a third on repeat testing is not a value to build a diagnosis or a treatment decision on. Fasting insulin also varies with recent meals, illness, sleep and stress.
| Test | Standardized? | Used to diagnose? |
|---|---|---|
| HOMA-IR | No agreed cut-off | No |
| Fasting glucose | Yes | Yes, 100 to 125 mg/dL is prediabetes |
| HbA1c | Yes, NGSP aligned | Yes, 5.7 to 6.4 percent is prediabetes |
| 75 g oral glucose tolerance test | Yes | Yes, two hour 140 to 199 mg/dL is prediabetes |
What a high HOMA-IR does tell you
A clearly high HOMA-IR in someone with central weight gain, a fatty liver or PCOS is consistent with insulin resistance, and it can be a useful conversation starter. It adds nothing that a fasting glucose, an HbA1c, a lipid panel and liver enzymes have not already told the clinician. A normal HOMA-IR in someone with a two hour glucose of 180 mg/dL does not reassure anyone.
If you already paid for a HOMA-IR, bring it. Then ask for the tests that carry a threshold and a treatment decision behind them: fasting glucose, HbA1c, and a two hour oral glucose tolerance test if those sit near the border. Repeat glucose testing in a year rather than repeating the HOMA-IR.
The clinical detail
HOMA-IR was derived from a computer solved model of glucose and insulin interaction. In the original validation the insulin resistance estimate correlated with euglycemic clamp measurements at Rs 0.88 and the beta cell estimate with hyperglycemic clamp at Rs 0.61, correlations that are strong at group level and weak for classifying one person.
Two practical problems remain. Each laboratory reports fasting insulin against its own reference interval, so a HOMA-IR calculated at one laboratory does not necessarily correspond to a value from another, and no professional society publishes a diagnostic threshold for it. The 2026 ADA Standards of Care define dysglycemia by fasting plasma glucose, two hour plasma glucose on a 75 g load, and A1C. Neither HOMA-IR nor fasting insulin appears in those criteria.
Written and medically reviewed by Zahraa Sater, M.D., M.P.H.
Reviewed August 12, 2026 · Next review due August 12, 2028
Sources
- Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia. DOI 10.1007/BF00280883
- Insulin Resistance and Prediabetes. National Institute of Diabetes and Digestive and Kidney Diseases
- 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes 2026. American Diabetes Association. PMID 41358893
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