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, with 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)
