Calculated from a single fasting glucose and insulin draw.
Source: Matthews et al., Diabetologia 1985.
What does HOMA-IR mean?
HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) is a mathematical model developed by Matthews and colleagues in 1985 to estimate insulin resistance from fasting glucose and fasting insulin concentrations. It is one of the most widely used surrogate markers of insulin resistance in clinical research and increasingly in clinical practice.
The formula is: HOMA-IR = (fasting glucose in mmol/L × fasting insulin in mIU/L) / 22.5. The divisor 22.5 normalises the equation so that a healthy young adult produces a value of approximately 1.0. In US units, the formula is: (fasting glucose mg/dL × fasting insulin mIU/L) / 405.
Insulin resistance means the body's cells respond poorly to insulin, requiring the pancreas to secrete more insulin to achieve the same glucose-lowering effect. Over time, this can lead to progressive beta-cell exhaustion, rising fasting glucose, and ultimately type 2 diabetes. Insulin resistance is also central to metabolic syndrome, polycystic ovary syndrome (PCOS), and non-alcoholic fatty liver disease.
HOMA-IR is a fasting, static measurement. It reflects primarily hepatic insulin resistance (how much insulin is needed to suppress liver glucose output) rather than peripheral (muscle) insulin resistance. The euglycaemic-hyperinsulinaemic clamp remains the gold standard but is impractical outside research settings.
Reference ranges
| HOMA-IR | Interpretation |
|---|---|
| < 1.0 | Optimal insulin sensitivity |
| 1.0 – 1.9 | Early insulin resistance / borderline |
| 2.0 – 2.9 | Insulin resistant |
| ≥ 3.0 | Significant insulin resistance; metabolic syndrome risk |
When should you see a doctor?
A HOMA-IR above 2.0, especially with other metabolic risk factors (abdominal obesity, high triglycerides, low HDL, or elevated blood pressure), warrants medical evaluation. Your doctor may recommend a glucose tolerance test, HbA1c measurement, or refer you to an endocrinologist or metabolic dietitian. Early intervention, lifestyle changes, can reverse insulin resistance before it progresses to type 2 diabetes.