HOMA-IR calculator

Bands commonly used in the literature

These bands describe how the index is used in published research. Cutoffs vary by population, by ethnicity and by insulin assay, which is exactly why no guideline body has endorsed a single number.

• Around 1.0 or below: Under 1.0. The value seen in lean, insulin sensitive reference populations. The original model was calibrated so that a healthy young adult sits near 1.
• 1.0 to 1.9: 1.0 to 1.9. Common in the general adult population. Frequently described in papers as early or mild reduction in insulin sensitivity rather than anything established.
• 2.0 to 2.9: 2.0 to 2.9. Above most reference populations. Studies using a threshold to define insulin resistance often place it somewhere in this range.
• 3.0 and above: 3.0 or higher. Consistently reported as insulin resistant across studies. Worth reviewing with the rest of your panel rather than in isolation.

What the index is doing

Matthews and colleagues described homeostatic model assessment in 1985 as a way to estimate insulin resistance and beta cell function from a single fasting sample, instead of running a clamp study that takes hours and a research team.

The logic is that if your glucose is normal only because your insulin is high, you are paying for that normal glucose. Multiplying the two captures that trade off, which is why a person with a perfectly ordinary glucose and a high insulin does not look reassuring on this index.

• US units: fasting insulin in µU/mL multiplied by fasting glucose in mg/dL, divided by 405.
• SI units: fasting insulin in mU/L multiplied by fasting glucose in mmol/L, divided by 22.5.

Why it is worth looking at early

Fasting insulin tends to rise years before fasting glucose does, and glucose is the number most annual physicals lean on. In the Whitehall II cohort, fasting glucose stayed close to flat for years and then rose steeply in the couple of years before diabetes was diagnosed, which is a poor early warning signal.

That is the practical argument for measuring insulin at all. It is not that HOMA-IR is precise. It is that it is looking at the part of the system that moves first.

What changes it

Direction is well established even where the magnitude is not. Weight loss, resistance and aerobic training, sleep repair and reduced alcohol intake all move fasting insulin down in intervention studies. Illness, poor sleep, corticosteroids and acute stress move it up.

One practical note on testing: this needs a genuine fast, usually 8 to 12 hours, and it should not be drawn during an acute illness or straight after unusually hard training, because both distort the result in ways that have nothing to do with your baseline.

Where this number is misleading

• Insulin assays are not standardized between laboratories, so results are not always comparable across labs.
• It is invalid in type 1 diabetes and unreliable in anyone taking insulin, because the fasting insulin is exogenous.
• It is a fasting index, so it says nothing about what happens to your glucose after a meal.
• A single value can be misleading. A repeat sample is more informative than a decision made on one draw.
• Pregnancy, polycystic ovary syndrome and steroid treatment all shift the interpretation and need clinical context.

Common questions

What is a normal HOMA-IR?

Lean insulin sensitive reference populations sit around 1.0 or below, and much of the general adult population sits between 1 and 2. There is no internationally agreed cutoff, partly because insulin assays differ between laboratories.

Can HOMA-IR be normal if I have insulin resistance?

Yes. It only looks at the fasting state. Some people have a normal fasting picture and a clearly abnormal response after eating, which a fasting index cannot see.

Do I need to fast for a HOMA-IR?

Yes. Both inputs must come from the same fasting sample, usually after 8 to 12 hours without food. A non fasting insulin makes the result meaningless.

Sources and disclosures

• Matthews DR, et al. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia, 1985.
• American Diabetes Association. Standards of Care in Diabetes, classification and diagnosis of diabetes.
• Tabak AG, et al. Trajectories of glycaemia, insulin sensitivity and insulin secretion before diagnosis of type 2 diabetes: the Whitehall II study. Lancet, 2009.
• These calculators are for education. They do not diagnose, they do not replace testing, and they are not a prescription. Baseline is a wellness consultancy, and any prescription is written by an independent licensed provider in our network who has reviewed your history, your goals and any lab work you choose to share.