Laboratory & Electrolytes

HOMA-IR (Insulin Resistance)

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.

Calculator

Glucose Units

mg/dLmmol/L

Fasting Plasma Glucose(mg/dL or mmol/L)Fasting ≥8 hours. Enter in units selected above.

Fasting Serum Insulin(µIU/mL)Fasting insulin in µIU/mL (= mU/L)

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Formula

HOMA-IR = (Fasting Glucose mmol/L × Fasting Insulin µIU/mL) / 22.5 Conversion: glucose mg/dL ÷ 18 = mmol/L <1.0: Insulin sensitive | 1.0–2.5: Normal | 2.5–5.0: Insulin resistance likely | >5.0: Significant resistance

Key Points for NEET PG

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)

For educational purposes only. Not for clinical decision-making without professional oversight.