What this calculator does
HOMA-IR estimates insulin resistance from a single fasting blood sample. It rests on a simple idea: if it takes more insulin to hold glucose at a given level, the tissues are responding to insulin less well.
Insulin does most of the moving. At a fasting glucose of 90 mg/dL, an insulin of 4 μU/mL gives 0.89 and an insulin of 25 gives 5.56, with glucose identical in both cases.
The formula
Multiply fasting glucose in mg/dL by fasting insulin in μU/mL and divide by 405. The constant normalises the result so a healthy young adult scores about 1.
| Term | Meaning |
|---|---|
| HOMA-IR | Homeostatic model assessment of insulin resistance. |
| Fasting insulin | Insulin measured after an overnight fast, the input that varies most. |
| Insulin resistance | Reduced tissue response to insulin, requiring more of it for the same effect. |
The inputs explained
| Field | What to enter |
|---|---|
| Fasting glucose (mg/dL) | Fasting glucose in mg/dL, from a blood sample after an overnight fast. |
| Fasting insulin (μU/mL) | Fasting insulin in μU/mL, from the same sample. Not part of a standard panel, so it must be requested. |
When to use it
Screening for insulin resistance
HOMA-IR is used in research and sometimes clinically to flag reduced insulin sensitivity.
Tracking a lifestyle change
Weight loss and exercise typically lower the index, often before other markers move.
Interpreting a fasting insulin result
Insulin alone is hard to read without the accompanying glucose.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much does fasting insulin move the index?
The same glucose at four fasting insulin levels.
| Fasting insulin | HOMA-IR | Commonly cited normal range |
|---|---|---|
| 4 μU/mL | 0.89 | below about 2.0 |
| 8 μU/mL | 1.78 | below about 2.0 |
| 16 μU/mL | 3.56 | below about 2.0 |
| 25 μU/mL | 5.56 | below about 2.0 |
Questions
What counts as a high HOMA-IR?
Above about 2.0 is commonly cited, but thresholds vary considerably between studies and populations, and insulin assays are not standardised between laboratories. The reference range on your own report matters more than a general figure.
Why is fasting insulin not on a standard panel?
Because it is not routinely needed for diagnosis, assays vary between laboratories and interpretation is not straightforward. It generally has to be requested specifically.
Is HOMA-IR a diagnosis?
No. It is a screening estimate derived from a mathematical model, and it does not diagnose diabetes, prediabetes or metabolic syndrome. Those require defined diagnostic criteria and clinical assessment.
How does it compare to a glucose tolerance test?
A clamp study or tolerance test measures insulin sensitivity directly and is far more accurate. HOMA-IR is an estimate from one fasting sample, which is its whole advantage and its whole limitation.
For average glucose over months rather than one morning, see the estimated average glucose calculator. For the lipid picture alongside it, see the cholesterol ratio calculator.