Quick Reference: Tests for Insulin Resistance – Part 1

Metabolic Health / By

Use this summary to discuss testing options with your clinician. Educational only; not medical advice.

Why These Tests

Insulin resistance is common, often silent for years, and contributes to cardiovascular, neurologic, and metabolic disease. Glucose tends to rise later; insulin rises earlier. Combining markers improves detection.

Fasting Glucose (FG)

  • Measures: Plasma glucose after an overnight fast
  • Typical reference: <100 mg/dL (≥100 mg/dL = prediabetes range)
  • Notes: Reflects mid–late changes

Hemoglobin A1c (HbA1c)

  • Measures: ~2–3 month average glucose
  • Typical reference: <5.7% (≥5.7% = prediabetes range)
  • Consideration: Risk may begin ~5.0%; use for trends

Fasting Insulin (FI)

  • Measures: Insulin after a fasting state (earlier signal)
  • Common reference: <10 µU/mL
  • Target used in video: 2–8 µU/mL
  • Notes: Elevated FI with normal glucose may suggest early resistance

HOMA-IR

  • Inputs: Fasting insulin + fasting glucose
  • Typical target: <1.5–2
  • Caveats: Optimized for non-diabetic cohorts; less reliable at extremes

QUICKI

  • Inputs: Fasting insulin + fasting glucose
  • Typical target: >0.34 (higher = more sensitive)
  • Strength: More stable across a wider range

Dynamic Assessments

Oral Glucose Tolerance Test (OGTT)

  • What it adds: Captures post-load glucose handling after a glucose load

Continuous Glucose Monitor (CGM)

  • Wear time: ~7–14 days
  • Use case: Personal response to meals, activity, sleep, medications
  • Limits: Evidence for diagnosing early resistance is evolving; some methods are “black box”
  • Important: May require calibration (default error can be ~±10%)

Lipids

  • Pattern: High triglycerides + low HDL in insulin resistance
  • Rule of thumb: Triglyceride/HDL ratio <2 (active debate)
  • Relevance: HDL participates in arterial plaque “cleanup”

Quick Targets at a Glance

  • Fasting Glucose: <100 mg/dL
  • A1c: <5.7% (risk may rise ~5.0%)
  • Fasting Insulin: <10 µU/mL (target 2–8 µU/mL)
  • HOMA-IR: <1.5–2
  • QUICKI: >0.34
  • TG/HDL Ratio: <2 (optimal cutoff varies by source)

Disclaimer: This guide is for educational purposes only and is not medical advice. Consult your clinician before testing or making health decisions.