Estimate insulin resistance using fasting glucose and insulin (Homeostatic Model Assessment).
When to use: Use HOMA-IR to quantify insulin resistance in patients with suspected metabolic syndrome, prediabetes, PCOS, non-alcoholic fatty liver disease (NAFLD/MASLD), or acanthosis nigricans. It requires fasting samples for both glucose and insulin. HOMA-IR correlates well with the gold-standard euglycaemic hyperinsulinaemic clamp and is practical for clinical use. Note that cut-offs vary between laboratories and populations; the 2.5 threshold is commonly used in India.
HOMA-IR formula: (glucose mmol/L × insulin µIU/mL) / 22.5 — both values must be fasting.
Cut-off for insulin resistance: HOMA-IR >2.5 (some studies use >2.0 or >3.0 — know the principle, not a single fixed number).
HOMA-IR is elevated in metabolic syndrome, PCOS, NAFLD, central obesity, acanthosis nigricans.
Metformin improves insulin sensitivity without causing hypoglycaemia — first-line drug for prediabetes and T2DM (also used in PCOS).
Indians have higher visceral adiposity and insulin resistance at lower BMI compared to Western populations — metabolic syndrome at lower waist cut-offs (90 cm male, 80 cm female by IDF Asia criteria).
References
Matthews DR et al. Homeostasis model assessment: insulin resistance and β-cell function from fasting plasma glucose and insulin concentrations in man · Diabetologia (1985)
Obesity and Type 2 Diabetes in South Asians: a systematic review of epidemiology and risk factors · Diabet Med (2018)
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