HOMA-IR Calculator

What HOMA-IR estimates

Homeostatic Model Assessment of Insulin Resistance, usually called HOMA-IR or HOMA1-IR, combines fasting glucose and fasting insulin to estimate the balance between hepatic glucose output and pancreatic insulin secretion in a resting state. A higher value means that more insulin is present for the accompanying glucose concentration, a pattern compatible with lower insulin sensitivity.

Matthews and colleagues introduced the model in 1985 as a practical fasting surrogate for more intensive research methods. The euglycemic hyperinsulinemic clamp directly examines glucose disposal during a controlled insulin infusion, while HOMA uses one fasting sample. HOMA is easier to apply in cohorts but gives less direct and less precise information for an individual.

Insulin resistance often produces no distinct symptoms. It can accompany prediabetes, type 2 diabetes, central adiposity, polycystic ovary syndrome, fatty liver disease, and some medication exposures. HOMA-IR does not diagnose any of these conditions.

ADA diagnostic criteria use A1C or plasma glucose, not fasting insulin or HOMA-IR.

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HOMA1-IR formula and units

For glucose in mmol/L, HOMA1-IR = fasting insulin in μU/mL × fasting glucose in mmol/L / 22.5. For glucose in mg/dL, HOMA1-IR = fasting insulin in μU/mL × fasting glucose in mg/dL / 405. The factor 405 is the rounded product of 22.5 and the conventional glucose conversion factor of 18.

Insulin reported as mIU/L has the same numerical value as μU/mL under the conventional unit expression used by most clinical reports. Do not substitute pmol/L without using the assay manufacturer's conversion information. Insulin conversions are not as universally interchangeable as glucose conversions because calibrators and molecular assumptions differ.

HOMA2 is a later computer model that accounts for nonlinear relationships and distinguishes some assay inputs. A HOMA2-IR result is not numerically interchangeable with HOMA1-IR from this calculator.

Record which model was used whenever results are compared.

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Worked HOMA-IR examples

With fasting glucose 95 mg/dL and fasting insulin 10 μU/mL, HOMA-IR = 95 × 10 / 405 = 2.35. In SI units, 95 mg/dL is about 5.27 mmol/L, so 5.27 × 10 / 22.5 = 2.34. The small difference comes from rounding the glucose conversion and constant.

With glucose 108 mg/dL and insulin 18 μU/mL, HOMA-IR = 108 × 18 / 405 = 4.80. The glucose also falls in the ADA impaired fasting glucose range of 100 to 125 mg/dL.

The fasting glucose has a defined diagnostic interpretation. HOMA-IR adds a research-style estimate but does not establish prediabetes or diabetes by itself.

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Why there is no universal cutoff

HOMA-IR has no ADA diagnostic threshold and no globally accepted healthy range. Published cutoffs depend on the reference population, insulin assay, age, sex distribution, ancestry, body composition, and whether investigators chose a percentile or optimized discrimination for metabolic syndrome. A Brazilian study reported HOMA1-IR above 2.7 for its healthy reference group, while other studies have produced lower or higher values.

A percentile cutoff answers how a person compares with a selected reference sample. A receiver operating characteristic cutoff answers how well the index separates groups under a chosen outcome definition. Neither creates a biological boundary where insulin sensitivity changes abruptly.

Labels such as normal, borderline, and resistant can overstate what one fasting calculation proves. The most defensible comparison uses a laboratory or study-specific reference based on the same insulin method and a relevant population. Serial results are easier to compare when the same laboratory, fasting conditions, and medications are maintained. Even then, day-to-day biological variation makes small changes uncertain.

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Diagnostic versus research use

HOMA-IR is widely used to rank insulin resistance in epidemiology and to compare group changes in intervention studies. It is not part of routine ADA screening criteria for diabetes. In clinical care, fasting insulin may be ordered for a specific endocrine question, but broad screening is limited by assay variation and the absence of standardized cutoffs.

Prediabetes and diabetes require validated glucose-based testing. For nonpregnant people, prediabetes includes fasting plasma glucose 100 to 125 mg/dL, two-hour glucose 140 to 199 mg/dL after a 75 g oral glucose load, or A1C 5.7% to 6.4%. Diabetes criteria include fasting glucose at least 126 mg/dL, two-hour glucose at least 200 mg/dL, or A1C at least 6.5%, with confirmation unless hyperglycemia is unequivocal.

A person can have a high fasting insulin while glucose remains within the laboratory reference interval because pancreatic insulin output is compensating. The reverse can occur when beta-cell function is impaired.

HOMA-IR becomes harder to interpret in advanced diabetes because the model assumes a functioning feedback loop between insulin secretion and glucose.

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Fasting and laboratory limitations

Use glucose and insulin from the same morning draw after the fasting interval specified by the ordering clinician or laboratory, commonly at least eight hours without calories. Water is generally allowed unless the laboratory says otherwise. A late meal, alcohol, acute illness, sleep loss, strenuous exercise, or smoking before collection can change the resting state the model assumes.

Glucose specimens can fall after collection because blood cells continue glycolysis. Prompt plasma separation or suitable handling reduces that error. Insulin is secreted in pulses and degrades if collection and storage are poor. These preanalytic effects can change the product in either direction.

Insulin immunoassays are not fully harmonized. Cross-reactivity with proinsulin and differences in antibodies or calibration limit comparisons between laboratories. Exogenous insulin also complicates interpretation, and some assays detect particular insulin analogs differently.

Results from people using insulin should not be entered without specialist interpretation.

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Population and clinical factors

Puberty and pregnancy are physiologic insulin-resistant states, so adult nonpregnant reference values do not transfer directly. Older age, menopause, central adiposity, liver disease, and kidney dysfunction can also shift fasting insulin or glucose. Population studies report different distributions across ancestry groups, but ancestry should not be treated as a fixed correction factor for an individual.

Glucocorticoids can raise glucose and insulin resistance, while acute stress hormones can disrupt fasting measurements. Polycystic ovary syndrome is associated with insulin resistance, but HOMA-IR neither confirms nor excludes the syndrome.

Type 1 diabetes, pancreatic disease, and long-standing type 2 diabetes with reduced insulin secretion fall outside the simple compensatory model. Interpretation is stronger when paired with the clinical question and established measures such as A1C, fasting glucose, lipids, blood pressure, medication history, and waist or other body-composition information. HOMA-IR may describe one mechanism. Cardiovascular and diabetes risk depend on a broader profile.

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Using the result constructively

A high value relative to an appropriate laboratory reference supports discussing the full metabolic picture, not starting a treatment from the calculator. Ask why fasting insulin was measured, whether the assay has a local reference interval, and whether established diabetes tests are due. Repeating a questionable sample under consistent conditions may be more useful than interpreting extra decimal places.

For people with laboratory-confirmed prediabetes, the CDC-recognized prevention approach centers on sustainable food, activity, and weight goals chosen with a care team. The Diabetes Prevention Program found that an intensive lifestyle program targeting at least 7% weight loss and 150 minutes of weekly activity reduced diabetes incidence by 58% over about 2.8 years. That evidence concerns people with impaired glucose tolerance, not treatment based on HOMA-IR alone.

Symptoms such as excessive thirst, frequent urination, unexplained weight loss, vomiting, or confusion require glucose assessment regardless of HOMA-IR.

A fasting surrogate cannot detect acute hyperglycemia safely and should not delay care.

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How to use this HOMA-IR calculator

Enter fasting glucose and fasting insulin from the same draw, select the glucose unit printed on the report, and confirm that insulin is in μU/mL or numerically equivalent mIU/L. Do not enter a post-meal insulin value, C-peptide, or an insulin value in pmol/L. Record the laboratory, collection date, fasting duration, and HOMA1 method.

Read the output as a continuous index. Avoid applying a cutoff taken from an unrelated population as a diagnosis.

If a previous result exists, compare only when the assay, laboratory, fasting preparation, medication context, and model are similar. Discuss a large or persistent change alongside glucose, A1C, symptoms, and the reason for testing. Do not adjust medication or insulin from this result. If fasting glucose is 100 mg/dL or higher, A1C is 5.7% or higher, symptoms are present, or risk is otherwise elevated, ask a clinician about validated diagnostic testing and follow-up.

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How it works

HOMA-IR = (fasting glucose × fasting insulin) / 405 (US units). >2.9 suggests significant insulin resistance.

Frequently asked questions

• What is a normal HOMA-IR?Values below 1.9 are generally normal. 1.9 to 2.9 is early resistance; ≥2.9 is significant resistance.

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References

1. Matthews et al.. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man
2. American Diabetes Association Professional Practice Committee. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes 2026
3. Wallace et al.. Use and abuse of HOMA modeling
4. National Institute of Diabetes and Digestive and Kidney Diseases. Insulin Resistance and Prediabetes
5. Gutch et al.. Assessment of insulin sensitivity and resistance
6. Geloneze et al.. HOMA1-IR and HOMA2-IR indexes in identifying insulin resistance and metabolic syndrome
7. National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes Tests and Diagnosis
8. Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin