HOMA-IR Calculator

HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) is a surrogate index of how well your body responds to insulin, calculated from a single pair of fasting blood draws: (fasting insulin in uIU/mL x fasting glucose in mg/dL) / 405. Matthews and colleagues published the model in Diabetologia in 1985 to give researchers a cheap proxy for the hyperinsulinemic-euglycemic clamp, which is the gold standard but takes hours and requires an IV infusion. A higher HOMA-IR means your pancreas is secreting more insulin to keep glucose in range, which is the hallmark of insulin resistance. HOMA-Beta, calculated alongside, estimates how hard your beta cells are working; QUICKI is a log-transformed sensitivity index from the same two inputs.

There is no universal clinical HOMA-IR cutoff. Values vary with the insulin assay, laboratory, age, puberty, population, body composition, and study definition. The calculator's under 1.0, 1.0 to 1.9, 2.0 to 2.9, and 3.0 or higher bands are internal descriptive labels, not diagnostic categories. Interpret a laboratory result with its method and a clinician rather than using the band to diagnose insulin resistance or diabetes.

The Matthews 1985 model assumes you are in the basal state, meaning at least 8 to 12 hours without food or caloric drinks. After a meal, insulin rises sharply for several hours and glucose follows a curve back to baseline; plugging post-meal values into the HOMA-IR equation would massively overestimate insulin resistance. The model also assumes you have not exercised vigorously that morning, are not acutely ill, and are not on medications that acutely shift insulin (such as a recent steroid dose). For the cleanest reading, draw blood first thing in the morning after a normal overnight fast, before any breakfast, coffee, or workout.

Toggle the units switch above the input from imperial (mg/dL, the US convention) to metric (mmol/L, used by the rest of the world). The calculator converts internally using the standard glucose molecular weight factor of 18.0156 mg/dL per mmol/L. The Matthews 1985 paper actually published the formula using mmol/L glucose with a denominator of 22.5 (22.5 x 18.0156 is about 405), so both unit systems give the same HOMA-IR; only the input scale changes. As reference points, fasting glucose of 100 mg/dL equals 5.55 mmol/L, and 126 mg/dL (the ADA diabetes diagnostic threshold) equals 7.0 mmol/L.

HOMA-IR is cheap, requires only one blood draw, and correlates reasonably well with clamp measurements at the population level, which is why it dominates large epidemiology studies. The trade-off is precision at the individual level. The hyperinsulinemic-euglycemic clamp directly measures insulin sensitivity but takes two to four hours and requires an infusion pump. An oral glucose tolerance test (OGTT) measures dynamic glucose handling over two hours and can detect impaired glucose tolerance that fasting numbers alone miss. HOMA-IR also depends heavily on the insulin assay your lab uses; different immunoassays can shift the absolute number by 20 to 30 percent. Use HOMA-IR as a screening signal, then follow up with OGTT, A1C, and a clinical assessment for anything ambiguous.