Endocrinology
HOMA-IR
Estimate of insulin resistance.
Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.
Background
The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) estimates insulin resistance from a single fasting blood sample, using paired fasting glucose and fasting insulin. It was developed from a mathematical model of glucose-insulin homeostasis that describes the feedback between hepatic glucose output and pancreatic insulin secretion. The simplified formula in common use is (fasting glucose in mmol/L × fasting insulin in mU/L) / 22.5. It is widely used in research and selected clinical contexts as a surrogate for more invasive measures of insulin sensitivity.
Interpreting the result
Higher values indicate greater insulin resistance. There is no universal cut-off because results depend heavily on the population studied and the insulin assay used, but as a rough guide values below about 2 are generally lower, around 2–3 intermediate, and above about 3 suggest insulin resistance is likely. Because thresholds vary, HOMA-IR is best interpreted against locally validated reference ranges and in the context of the wider metabolic picture rather than as a fixed diagnostic line.
Worked example
A patient has a fasting glucose of 5.5 mmol/L and a fasting insulin of 12 mU/L: HOMA-IR = (5.5 × 12) / 22.5 ≈ 2.9. This is in the intermediate range and, taken with other metabolic features, may prompt consideration of insulin resistance.
Critical actions
HOMA-IR = (fasting glucose mmol/L × fasting insulin mU/L) / 22.5. Thresholds vary by population and assay; interpret with caution.
Pearls / pitfalls
- The sample must be truly fasting; non-fasting glucose or insulin invalidates the result.
- Insulin assays are not standardised, so HOMA-IR values are not directly comparable between laboratories.
- It is unreliable in people on insulin therapy and of limited use where beta-cell function is failing (e.g. advanced type 2 diabetes).
- It is an epidemiological and research tool — there is no single agreed clinical threshold, so do not over-interpret a borderline value.
Evidence & validation
Originally described by Matthews and colleagues, who derived the model and validated it against clamp-based and other reference measures of insulin sensitivity. It remains a widely used research index but is not endorsed as a stand-alone diagnostic test for diabetes or the metabolic syndrome.
Frequently asked questions
What is a normal HOMA-IR?
There is no single normal value because it depends on the population and the insulin assay. As a rough guide, values below about 2 are often considered lower and values above about 3 suggest insulin resistance is likely, but locally validated ranges should be used.
Do I need to be fasting?
Yes. HOMA-IR requires fasting glucose and fasting insulin measured on the same sample. A non-fasting result is not valid and should not be used.
Can HOMA-IR diagnose diabetes?
No. It is a surrogate index of insulin resistance, mainly used in research and selected clinical contexts. Diabetes is diagnosed using glucose and HbA1c criteria, not HOMA-IR.
Why can results differ between laboratories?
Insulin assays are not standardised across laboratories, so the same patient can give different insulin values and therefore different HOMA-IR results. This is why population-specific and assay-specific reference ranges matter.
References
- Matthews DR, Hosker JP, Rudenski AS, et al. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia. 1985;28(7):412–419.
- Wallace TM, Levy JC, Matthews DR. Use and abuse of HOMA modeling. Diabetes Care. 2004;27(6):1487–1495.
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