HOMA-IR Test: How to Calculate It and What It Says About Insulin and Energy

Short answer: The HOMA-IR test is not a separate blood draw. It is a score calculated from two fasting lab values: fasting insulin multiplied by fasting glucose, divided by 22.5 (glucose in mmol/L) or by 405 (glucose in mg/dL). A higher number suggests your body needs more insulin to keep fasting glucose steady, which points toward insulin resistance. There is no single universal cutoff, insulin resistance usually causes no symptoms, and a score is not an energy test, so read it with your doctor alongside A1C and fasting glucose.

Key Takeaways

• Simple formula: HOMA-IR = (fasting insulin × fasting glucose) / 22.5, with insulin in µU/mL and glucose in mmol/L. Use 405 instead of 22.5 when glucose is reported in mg/dL.
• Research roots: The method comes from a 1985 Diabetologia paper in which the score correlated strongly with the euglycemic clamp, the research gold standard (Rs = 0.88).^[3]
• Cutoffs vary: Published thresholds differ by population, lab assay and study design. A large Korean survey, for example, linked about 1.6 with dysglycemia and 2.87 (men) with type 2 diabetes.^[6]
• Not how diabetes is diagnosed: NIDDK says doctors generally do not test for insulin resistance; prediabetes is diagnosed with A1C, fasting plasma glucose or an oral glucose tolerance test.^[1]
• Fatigue is a poor clue: People with insulin resistance and prediabetes usually have no symptoms, so low energy needs its own medical workup.^[1]
• Lifestyle is the first lever: In the Diabetes Prevention Program, losing 5% to 7% of starting weight lowered the chance of developing type 2 diabetes in high risk adults.^[1]

What the HOMA-IR Test Measures

HOMA stands for homeostasis model assessment. The idea, published by Matthews and colleagues in 1985, is that your fasting glucose and fasting insulin settle into a balance set by a feedback loop between the liver and the pancreas. By comparing your two fasting values with what a computer model predicts, researchers can estimate how much of a high fasting glucose comes from insulin resistance and how much comes from weak beta cell output.^[3]

HOMA-IR is the insulin resistance half of that model. HOMA-B (or HOMA %B) is the beta cell half. When your doctor orders “HOMA-IR,” the lab is usually just running a fasting insulin and a fasting glucose on the same sample and doing the arithmetic.

Why it exists

The most accurate way to measure insulin sensitivity is the euglycemic hyperinsulinemic clamp, a multi-hour infusion test done in research units. HOMA-IR is a cheaper, less invasive estimate. In the original paper it correlated with the clamp at Rs = 0.88, but the authors also reported a coefficient of variation of about 31%, which they said limits its precision.^[3] A later study of 90 adults (normal glucose tolerance, impaired glucose tolerance and type 2 diabetes) found a moderate correlation with the clamp (r = -0.558 after log transformation) and weaker agreement in leaner people and in those with low beta cell function.^[5]

How to Calculate HOMA-IR (With Examples)

The widely used approximation, sometimes called HOMA1-IR, is:^[4]

HOMA-IR = fasting insulin (µU/mL) × fasting glucose (mmol/L) / 22.5

Most US labs report glucose in mg/dL. Because 1 mmol/L of glucose equals about 18 mg/dL, the constant becomes 22.5 × 18 = 405:

HOMA-IR = fasting insulin (µU/mL) × fasting glucose (mg/dL) / 405

The table below works through a few sample numbers so you can see how the score moves. These are illustrations of the arithmetic, not diagnostic categories.

Notice how much the result depends on insulin. Two men with the same fasting glucose of 90 mg/dL can land at 1.1 or 4.4 simply because one needs four times the insulin to hold that glucose level. That is the main reason people ask for the test: fasting glucose can look normal while insulin is quietly working harder.

Getting a clean result

• Fast properly. Both values must be true fasting values, usually after an overnight fast. Ask your lab for its exact instructions.
• Same draw. Insulin and glucose should come from the same blood sample.
• Know the assay. The 1985 equation was calibrated to an older insulin assay, and insulin assays have historically varied a lot between labs, so comparing scores from different labs is unreliable.^[4]
• Repeat if it matters. Wallace and colleagues note that a single sample is more variable than the average of three, and suggest repeated samples when HOMA is used for an individual.^[4]
• Not for insulin users. The score does not apply to people injecting insulin, and some diabetes drugs change the beta cell estimate.^[4]

HOMA-IR Normal Range: Why There Is No Single Cutoff

This is the part most online calculators skip. The HOMA model is anchored so that a normal reference population has an IR value of about 1 (and an insulin sensitivity of 100%).^[4] Beyond that anchor, there is no official diagnostic threshold. The 2004 Diabetes Care review “Use and Abuse of HOMA Modeling” stresses that each population needs its own normal glucose reference group before anyone can call a value abnormal, and that HOMA is best suited to studies of groups and to tracking change over time.^[4]

Published cutoffs illustrate the spread. In 4,291 Korean adults not taking diabetes drugs, a HOMA-IR around 1.6 best identified dysglycemia, while values of 2.87 in men and 2.36 in women identified type 2 diabetes. The authors noted that cutoffs in other studies vary with the population, sample size and diagnostic criteria, and that ethnic differences exist.^[6] Other studies in other countries report different numbers, which is why you will see “normal” quoted anywhere from about 1 to 3 on different websites.

The practical takeaway: a result near 1 is reassuring, a result that is clearly higher deserves a conversation with your doctor, and the trend over time (using the same lab) usually tells you more than any single cutoff.

HOMA-IR vs A1C, Fasting Glucose and the Glucose Tolerance Test

According to NIDDK, doctors generally do not test for insulin resistance in routine care; that kind of testing is mainly used in research. What they do test for is prediabetes and diabetes.^[1]

NIDDK notes that A1C can miss prediabetes in people with certain health conditions, and that the glucose tolerance test is harder to give, takes longer and costs more.^[1][2] Your doctor may also check cholesterol and triglycerides. If your results are normal but you have risk factors, NIDDK suggests retesting at least every 3 years; if prediabetes is found, testing for type 2 diabetes is suggested yearly.^[1]

Does a High HOMA-IR Explain Low Energy?

Not on its own. NIDDK is clear that people with insulin resistance and prediabetes usually have no symptoms.^[1] Afternoon crashes, brain fog and poor workouts have many possible causes: short or broken sleep, sleep apnea, low iron, thyroid problems, low B12, depression, alcohol, medicines and more. A high HOMA-IR is a reason to look at metabolic health, not proof that insulin is the cause of your fatigue.

Who is more likely to have insulin resistance

NIDDK lists these risk factors:^[1]

• Overweight, obesity or a large waist
• Age 35 or older
• Family history of diabetes
• African American, Hispanic or Latino, American Indian, Asian American or Pacific Islander background
• Physical inactivity
• Smoking, vaping or secondhand smoke
• Conditions such as sleep apnea, Cushing’s syndrome or acromegaly
• Long term use of certain medicines, such as glucocorticoids, some antipsychotics and some HIV medicines

If sleep apnea is on your radar, our guide to sleep apnea and testosterone explains why it deserves a proper sleep study. Many men with metabolic risk also hear about liver fat at the same visit; see fatty liver and testosterone for what that link looks like.

How to Improve Insulin Sensitivity: What NIDDK Recommends

The steps with the strongest evidence are not exotic. NIDDK points to healthy eating, regular physical activity, weight management and enough sleep.^[1]

• Modest weight loss: In the Diabetes Prevention Program, adults at high risk who lost 5% to 7% of their starting weight reduced their chance of developing diabetes, and follow up showed the benefits lasted at least 15 years.^[1]
• Move more: The DPP lifestyle program combined diet changes with more physical activity. Your doctor can help you set a safe target, especially if you have heart disease or joint problems.
• Sleep: NIDDK includes enough sleep in its healthy living advice. Our sleep routine guide for men covers the basics.
• Stop smoking and vaping: Both are on NIDDK’s risk factor list.

Medicines

NIDDK notes that metformin can help manage blood glucose and may delay or prevent type 2 diabetes in some people at high risk; in the DPP it worked best in younger adults, people with obesity and women with a history of gestational diabetes.^[1] Whether you need medicine is a decision for you and your doctor. If you already take it and wonder about hormones, read our neutral review of metformin and testosterone.

Once you start making changes, recheck with the same lab and the same fasting routine so the numbers are comparable.

A Note on Supplements and Blood Sugar

No supplement replaces lab testing, lifestyle change or prescribed treatment for insulin resistance, and Ultra Bann is not designed or marketed for blood sugar or insulin. It is a male vitality supplement with seven botanicals listed in full on the Ultra Bann ingredients page.

One of those botanicals matters for this topic. Ultra Bann contains 110 mg of Panax ginseng per capsule. NCCIH reports that some evidence suggests Asian ginseng might lower blood sugar levels, that research on blood sugar control in people with diabetes is inconclusive and conflicting, and that people with diabetes should consult their health care provider before using it.^[7] NCCIH also lists insomnia as its most common side effect and notes it may interact with certain medications.^[7] If you take metformin, insulin or any other glucose lowering medicine, ask your doctor before adding any ginseng product. More detail is in our article on Panax ginseng for men.

Frequently Asked Questions

What is a normal HOMA-IR score?

There is no single official normal range. The model is anchored so a normal reference population scores about 1, and published cutoffs for insulin resistance differ by population and lab method. One Korean study linked about 1.6 with dysglycemia and 2.87 (men) with type 2 diabetes. Ask your doctor how your lab interprets its own results.

How do I calculate HOMA-IR from my lab results?

Multiply fasting insulin (µU/mL) by fasting glucose. Divide by 405 if glucose is in mg/dL, or by 22.5 if it is in mmol/L. For example, insulin 10 and glucose 90 mg/dL gives 10 × 90 / 405, or about 2.2.

Do I need to fast for a HOMA-IR test?

Yes. The formula only works with fasting insulin and fasting glucose, usually after an overnight fast. Eating before the test raises both values and makes the score meaningless.

Is HOMA-IR better than A1C?

They answer different questions. A1C reflects average glucose over the past few months and is used to diagnose prediabetes and diabetes. HOMA-IR estimates insulin resistance and is not a diagnostic test. Doctors rely on A1C, fasting plasma glucose and the glucose tolerance test for diagnosis.

Can insulin resistance make you tired?

Insulin resistance usually causes no symptoms, according to NIDDK. Fatigue has many possible causes, so a high score should prompt a broader checkup rather than self treatment.

References

1. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Insulin Resistance & Prediabetes.
2. NIDDK. Recommended Tests for Identifying Prediabetes.
3. Matthews DR, et al. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia. 1985. Abstract.
4. Wallace TM, Levy JC, Matthews DR. Use and Abuse of HOMA Modeling. Diabetes Care. 2004;27(6):1487 to 1495. Full text (PDF).
5. Study comparing HOMA-IR with the euglycemic hyperinsulinemic clamp in 90 adults. PubMed abstract, PMID 15690315.
6. Baek JH, Kim H, Kim KY, Jung J. Insulin Resistance and the Risk of Diabetes and Dysglycemia in Korean General Adult Population. Diabetes & Metabolism Journal. 2018;42(4):296 to 307. Article.
7. National Center for Complementary and Integrative Health (NCCIH). Asian Ginseng.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. This article is for information only and is not medical advice.