The formula
HOMA-IR = (Fasting Glucose mg/dL × Fasting Insulin mIU/mL) / 405
For SI units: HOMA-IR = (Fasting Glucose mmol/L × Fasting Insulin mU/L) / 22.5
Both produce the same number scale.
Interpretation ranges
- <1.0: Optimal insulin sensitivity
- 1.0-2.0: Borderline insulin resistance
- 2.0-3.5: Insulin resistance
- >3.5: Significant insulin resistance
Validation against gold standard
The euglycemic-hyperinsulinemic clamp is the gold-standard test of insulin sensitivity but requires an IV, fluid infusions, and hours of testing. HOMA-IR correlates with clamp results well enough for clinical use, at a fraction of the time and cost.
When to use it
- Initial metabolic evaluation
- Tracking response to lifestyle changes
- Tracking response to GLP-1 therapy or other interventions
- Identifying compensated insulin resistance (normal glucose, elevated insulin)
- Risk stratification for diabetes development
Tracking across visits
HOMA-IR is one of the most responsive metabolic markers to therapy:
- Lifestyle interventions: 10-30% reduction over 3-6 months
- GLP-1 therapy: 40-60% reduction
- Significant weight loss: 50%+ reduction
Watching HOMA-IR drop over months is one of the most concrete signs of metabolic improvement.
The clinical pearl: HOMA-IR is calculable for free if fasting insulin and glucose are tested. It gives a single interpretable score for insulin resistance. Add fasting insulin to your routine panels to enable this calculation.
Bottom line
HOMA-IR converts fasting glucose and insulin into an interpretable insulin resistance score. Optimal under 1.0. Tracks metabolic improvement faster than HbA1c. Calculable from any panel that includes fasting insulin.