MetabolicUpdated 2025-12-24Medically Reviewed
Fasting Insulin
Everything you need to know about Fasting Insulin levels, including what normal ranges look like and what abnormal results might indicate.
Standard Reference Range
Unit: µIU/mLMale Reference Range
2 - 10 (optimal 2-5) µIU/mL
Female Reference Range
2 - 10 (optimal 2-5) µIU/mL
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Reference ranges may vary slightly between laboratories. Always consult your doctor for interpretation.
What is fasting insulin?
Fasting insulin measures how much insulin your pancreas releases after 8–12 hours without food. It uncovers insulin resistance earlier than glucose or HbA1c.
Key takeaway
Insulin often rises years before blood sugar drifts upward. Pair it with glucose to calculate HOMA-IR.
Why is this test performed?
- Detect early insulin resistance and metabolic syndrome
- Guide nutrition and training adjustments
- Track response to weight loss, low-carb plans, GLP-1/SGLT2/metformin therapy
How to prepare
- 8–12 hour fast, water allowed
- Avoid intense exercise and alcohol 24 hours prior
- Morning draw preferred to reduce cortisol variation
Interpreting your result
- Optimal 2–5 µIU/mL: high insulin sensitivity
- 5–10: watch diet/activity; recalc HOMA-IR in 3–6 months
- ＞10: likely insulin resistance—adjust lifestyle; consider clinician review
Related tests and actions
- Combine with fasting glucose → HOMA-IR
- Elevated? Prioritize strength training, Zone2 cardio, protein adequacy, lower refined carbs
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