What Is HOMA-IR?
Medically reviewed by Dr. Chhaya Makhija, MD, DipABLM — October 2026
By Ryan Mitchell · Referenced to Matthews et al. 1985
HOMA-IR — the Homeostatic Model Assessment of Insulin Resistance — estimates how resistant your body is to insulin using just two fasting blood values: glucose and insulin. Introduced by Matthews and colleagues in 1985, it's one of the most widely used research and screening tools for insulin resistance because it needs no special test beyond a routine fasting draw. You may also see it written as the HOMA index, HOMA score, or simply HOMA — these all refer to the same calculation.
The HOMA-IR test: how it's ordered and done
There is no single "HOMA-IR blood test" you can request by name. HOMA-IR is a calculation derived from two ordinary lab results — fasting plasma glucose and fasting insulin — drawn from the same morning blood sample. Your clinician orders those two tests; the HOMA-IR score is worked out afterward from the numbers.
| Step | What happens |
|---|---|
| Fasting | 8–12 hours with water only — no food, caloric drinks, or coffee beforehand |
| Timing | Early-morning draw, before eating, heavy exercise, or the day's medications where advised |
| What's measured | Fasting plasma glucose (mg/dL or mmol/L) + fasting serum insulin (µIU/mL or pmol/L) |
| The result | HOMA-IR = (glucose × insulin) ÷ 405 — computed from the two values, not a separate assay |
| Turnaround | Same as a routine metabolic panel; the score is derived once both values return |
Because insulin assays are not standardized between laboratories, a HOMA-IR score is most reliable when tracked at the same lab over time rather than compared across providers. If your lab reports insulin in pmol/L, convert to µIU/mL by dividing by 6.0 before using the 405 formula (older references use 6.945, which under-reads insulin by about 15%), or use our HOMA-IR calculator, which handles both unit systems.
The formula
Using glucose in mg/dL and insulin in µU/mL, the divisor is 405. If glucose is measured in mmol/L, the divisor is 22.5 instead. Example: glucose 95 mg/dL (5.3 mmol/L), insulin 12 µU/mL → (95 × 12) ÷ 405 = 2.8.
Normal range and interpretation
| HOMA-IR score | General interpretation* |
|---|---|
| < 1.0 | Optimal insulin sensitivity |
| 1.0 – 1.9 | Normal / early-optimal range |
| 2.0 – 2.9 | Emerging / possible insulin resistance |
| ≥ 3.0 | Significant insulin resistance likely |
*Cut-offs vary by lab, assay, and population — some studies use 2.5 or ethnicity-specific thresholds. Always interpret against your own lab's reference range.
Why it matters — PCOS, NAFLD, prediabetes
Insulin resistance sits upstream of many conditions, often years before blood glucose rises enough to flag on standard tests. A raised HOMA-IR is commonly seen in and used to monitor:
- Type 2 diabetes & prediabetes — resistance is the core defect long before diagnosis.
- PCOS — insulin resistance drives much of the hormonal picture; HOMA-IR is a common workup value.
- NAFLD / metabolic-associated fatty liver disease — closely tracks hepatic insulin resistance.
- Metabolic syndrome — resistance links the cluster of hypertension, dyslipidemia and central adiposity.
Because it catches the problem early, a rising HOMA-IR is often the trigger for lifestyle intervention — the window where diet, activity and weight change reverse resistance most effectively.
HOMA-IR vs HOMA2, HOMA-β and the other indices
The 1985 formula on this page is the HOMA1 model. In 1998 the same Oxford group published HOMA2 — a computer-based update that better handles higher glucose levels and different insulin assays; it must be run through the official HOMA2 calculator rather than by hand. For everyday screening the simple HOMA1 score is still the most widely quoted. A closely related output, HOMA-β (HOMA-B), uses the same two fasting values to estimate beta-cell function — how hard your pancreas is working — rather than resistance. Insulin resistance scores sit alongside dosing tools in our insulin and metabolic calculators.
| Index | Measures | Notes |
|---|---|---|
| HOMA-IR (HOMA1) | Insulin resistance | Manual formula, ÷405 or ÷22.5 — this page |
| HOMA2-IR | Insulin resistance (refined) | Requires the official HOMA2 software model |
| HOMA-β / HOMA-B | Beta-cell function | Pancreatic output, not resistance |
| QUICKI | Insulin sensitivity | Log-transformed; more stable at low insulin |
| Triglyceride:HDL | Insulin resistance (surrogate) | Lipid-based, no insulin assay needed |
| Glucose:insulin ratio | Insulin resistance (screening) | Simplest fasting ratio |
HOMA-IR chart: your score from glucose and insulin
Find your fasting glucose down the side and your fasting insulin (µIU/mL) across the top. Each cell is (glucose × insulin) ÷ 405, rounded to one decimal.
| Glucose (mmol/L) | Insulin 5 | Insulin 10 | Insulin 15 | Insulin 20 | Insulin 25 |
|---|---|---|---|---|---|
| 80 mg/dL (4.4) | 1.0 | 2.0 | 3.0 | 4.0 | 4.9 |
| 90 mg/dL (5.0) | 1.1 | 2.2 | 3.3 | 4.4 | 5.6 |
| 100 mg/dL (5.6) | 1.2 | 2.5 | 3.7 | 4.9 | 6.2 |
| 110 mg/dL (6.1) | 1.4 | 2.7 | 4.1 | 5.4 | 6.8 |
| 120 mg/dL (6.7) | 1.5 | 3.0 | 4.4 | 5.9 | 7.4 |
What lowers HOMA-IR?
HOMA-IR falls when insulin resistance falls, and the same habits that lower diabetes risk drive it down. The strongest evidence comes from the Diabetes Prevention Program trial, published in 2002. People with prediabetes who lost about 7% of their body weight and did 150 minutes of brisk activity a week cut their risk of type 2 diabetes by 58% over about three years.
- Weight loss: losing 5–7% of body weight lowers fasting insulin, so the score drops even before glucose changes.
- Physical activity: working muscle takes up glucose with less insulin; aim for at least 150 minutes a week plus some strength training.
- Sleep and illness: short sleep, acute illness and steroid medicines all raise insulin resistance for a while, so retest after recovery.
- Medicines: metformin and other diabetes drugs change both inputs; test on the same treatment each time to compare like with like.
Retest in the same lab after 3–6 months of change, because insulin assays differ between labs.
Limitations
- Fasting only. Values must come from an 8–12 hour fast; non-fasting samples invalidate the result.
- Assay-dependent. Insulin assays aren't standardized, so scores aren't perfectly comparable between labs.
- Not for insulin-treated diabetes. Injected insulin makes the "fasting insulin" input meaningless.
- Single snapshot. One value can mislead; trends over time are more informative.
Do HOMA-IR cutoffs change with age and sex?
Yes — and this is one of the most common misreadings of a HOMA-IR result. The same fasting glucose and insulin values can land differently depending on who is being measured, because insulin sensitivity and beta-cell output both shift across a lifetime.
- Sex: a study of Korean adults aged 65 and over placed the cutoff for type 2 diabetes at roughly 2.25 in men and 2.03 in women — men run slightly higher on average. For prediabetes the ordering reverses, with women showing the higher cutoff.
- Population norms: in NHANES III data (Bravata et al., 2004), US adults without diabetes had a median HOMA-IR of 2.2 and a mean of 2.8 — so a result slightly above the tidy “normal” band can still sit below the average American adult.
- Pediatric use: children and adolescents have different reference ranges again, and cutoffs in youth studies tend to sit higher than the adult 2.5 line. A paediatric result should be interpreted against paediatric norms, not adult ones.
The practical takeaway: treat any single cutoff as a population statistic, not a personal verdict. Our HOMA-IR calculator covers the sex-specific cutoffs and the HOMA1 vs HOMA2 calibration issue in detail.
Frequently Asked Questions: What Is HOMA-IR?
What is a normal HOMA-IR?
Values under about 1.0 suggest optimal insulin sensitivity and roughly 1.0–1.9 is generally treated as normal in adults, with 2.0–2.9 borderline and 3.0 or above suggesting insulin resistance. No endocrine society has ratified a single universal cutoff, and thresholds shift with sex, ancestry and the insulin assay your lab uses.
Do I need to fast before a HOMA-IR test?
Yes. The calculation requires genuinely fasting glucose and insulin drawn from the same sample, normally after 8–12 hours with nothing but water. Anything with calories beforehand raises both inputs and inflates the score, making the result meaningless.
What is the difference between HOMA-IR and HOMA2?
HOMA-IR is the 1985 hand equation. HOMA2 is a later non-linear computer model that corrects for hepatic versus peripheral glucose resistance, the insulin secretion curve above 180 mg/dL (10.0 mmol/L), and circulating proinsulin, and it can run on C-peptide. Because the 1985 equation was calibrated to 1970s insulin assays, it tends to underestimate insulin sensitivity against modern lab results.
Can HOMA-IR be normal if I have insulin resistance?
Yes, and this is the score’s most important blind spot. HOMA-IR depends on how much insulin your pancreas is still producing. In longer-standing Type 2 diabetes, beta-cell output falls while resistance persists, so the score can drop even as the underlying problem worsens. A falling HOMA-IR alongside rising glucose is a warning sign, not progress.
Does a high HOMA-IR mean I have diabetes?
No. HOMA-IR is a screening estimate, not a diagnostic test, and no guideline uses it to diagnose anything. Diabetes and prediabetes are diagnosed from fasting glucose, HbA1c or an oral glucose tolerance test. A raised HOMA-IR is a reason to test properly, not a result to act on alone.
How can I lower my HOMA-IR score?
Lower fasting insulin by improving insulin sensitivity. In the Diabetes Prevention Program, losing about 7% of body weight and doing 150 minutes of brisk activity a week cut progression to type 2 diabetes by 58%. Better sleep, recovery from illness and some medicines also lower the score. Retest at the same lab after 3–6 months.
What is the HOMA index?
The HOMA index (homeostatic model assessment) is the umbrella term for the indices derived from fasting glucose and fasting insulin: HOMA-IR for insulin resistance, HOMA-%B for beta-cell function and HOMA-%S for sensitivity. When a lab report mentions the HOMA index without naming one, it almost always means HOMA-IR.
Sources & References
- Matthews DR, Hosker JP, Rudenski AS, et al. Homeostasis model assessment: insulin resistance and β-cell function from fasting plasma glucose and insulin. Diabetologia. 1985;28(7):412-9. Link
- Wallace TM, Levy JC, Matthews DR. Use and abuse of HOMA modeling. Diabetes Care. 2004;27(6):1487-95. Link
- NIDDK. Insulin Resistance & Prediabetes. Link
- Knopp JL, Holder-Pearson L, Chase JG. "Insulin Units and Conversion Factors: A Story of Truth, Boots, and Faster Half-Truths." J Diabetes Sci Technol. 2019. — why 6.00, not 6.945, converts pmol/L to µIU/mL. Link
- Association of Insulin Resistance with Dysglycemia in Elder Koreans: Age- and Sex-Specific Cutoff Values (KNHANES 2019–2021, adults ≥65). — source of the 2.25/2.03 and 1.73/1.85 cutoffs. Link
- Bravata DM, Wells CK, Concato J, et al. "Two measures of insulin sensitivity provided similar information in a U.S. population." J Clin Epidemiol. 2004;57:1214–1217. — NHANES III median 2.2, mean 2.8. Link
- Diabetes Prevention Program Research Group. "Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin." N Engl J Med. 2002;346:393–403. Link
Written by Ryan Mitchell · Last updated: October 2026