Fasting Insulin Interpreter
Your lab says "in range." But in range is not optimal. Enter your fasting insulin to see where you really stand, and add your glucose to calculate HOMA-IR right here.
Your fasting insulin
Enter your fasting insulin level. Optionally add fasting glucose to calculate your HOMA-IR score inline.
Both values must be from a fasting blood sample. Insulin is often not on standard panels — you may need to request it.
What this means
What to consider
Medications that may affect your result
Metformin reduces hepatic glucose output and improves insulin sensitivity, which typically lowers fasting insulin over time. Your unmedicated insulin level would likely be higher.
Corticosteroids (prednisone, dexamethasone) increase insulin resistance and can raise fasting insulin, sometimes significantly with prolonged use.
Atypical antipsychotics (olanzapine, clozapine, quetiapine) are associated with increased insulin resistance and elevated fasting insulin, independent of weight gain.
Exogenous insulin — if you are on insulin therapy, this tool does not apply. Measured fasting insulin reflects both endogenous and exogenous insulin and cannot be meaningfully interpreted.
If you are taking any of these medications, your results reflect the medicated state. Discuss trends and targets with your healthcare provider.
About this tool
Thresholds
Optimal: below 5 μIU/mL. Acceptable: 5-9 μIU/mL. Borderline: 10-15 μIU/mL. Elevated: above 15 μIU/mL. These are functional/metabolic health thresholds and are narrower than the standard laboratory reference range of 2-25 μIU/mL.
Inline HOMA-IR Formula
HOMA-IR = (Fasting Insulin × Fasting Glucose in mg/dL) / 405. If glucose is entered in mmol/L, it is converted to mg/dL first (×18.018). HOMA-IR optimal: below 1.0. Healthy: 1.0-1.9. Borderline: 2.0-2.9. Significant: 3.0 and above.
Known Limitations
Fasting insulin has significant intra-individual variability — a single measurement is a snapshot. Optimal thresholds (below 5 μIU/mL) are derived from metabolic health research and differ from standard lab "normal" ranges, which are population-based and include people with early insulin resistance. Not valid for people on exogenous insulin therapy. Insulin levels can be acutely affected by recent meals, stress, sleep deprivation, and time of blood draw.
Sources
Kraft JR. "Detection of diabetes mellitus in situ (occult diabetes)." Laboratory Medicine, 1975. Reaven GM. "Role of insulin resistance in human disease." Diabetes, 1988. Wallace TM, et al. "Use and abuse of HOMA modeling." Diabetes Care, 2004.
Educational tool only. Not for diagnostic purposes. Consult a healthcare provider for medical decisions.