Can this result diagnose a condition on its own?

No. Laboratory results are interpreted with symptoms, medical history, sampling conditions, and related tests.

Which reference range or cutoff should I use?

Start with the performing laboratory's report and the purpose of testing; diagnostic cutoffs are separate sourced clinical thresholds.

When should I discuss the result with a healthcare professional?

Results that are clearly outside range, persistent, symptomatic, or unexpected should be reviewed by a healthcare professional.

Information about a laboratory test

Insulin: What Does This Test Measure?

Measures insulin in the blood; insulin is a pancreatic hormone that helps move glucose into cells.

Test summary

Test name: Insulin
Abbreviations: Fasting Insulin, Serum Insulin
Category: Endocrinology / Glucose Metabolism
Panel: Glucose / Insulin Metabolism
Specimen: Serum / plasma
Common units: µIU/mL, mIU/L, pmol/L

What does the test measure?

Measures insulin in the blood; insulin is a pancreatic hormone that helps move glucose into cells.

Why is the test ordered?

May be ordered with glucose and C-peptide in selected evaluations of hypoglycemia, insulin production, or metabolic disorders.

Information about a low result

Low insulin may reflect reduced insulin production or sampling context and is interpreted with glucose and C-peptide.

Information about a high result

High insulin can occur in several settings including insulin resistance, but the value alone does not diagnose insulin resistance.

Reference and clinical context

Use the performing laboratory's report and the sampling conditions first. Fasting status, timing, and whether the test is diagnostic or for monitoring can change interpretation.

Reference ranges may vary by laboratory, method used, age, sex, pregnancy status, and clinical context. The reference range on your own laboratory report takes precedence.

Interpretation notes

Insulin reference intervals vary by assay and fasting status. Interpret with glucose and, when relevant, C-peptide.

Related specialties

Endocrinology
Internal Medicine
Family Medicine
Pediatric Endocrinology

Frequently asked questions

More information about this test

Sources

Blood Glucose Test — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2026 · Blood glucose purpose, high/low context and related testing · Verified: Aug 12, 2026
Insulin in Blood — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2026 · Insulin blood testing and interpretation with glucose/C-peptide · Verified: Aug 12, 2026
C-Peptide Test — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2026 · C-peptide use for endogenous insulin production and hypoglycemia context · Verified: Aug 12, 2026