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Insulin, Serum/Plasma — Substance Concentration

Published: August 9, 2026Updated: August 16, 2026

Measures insulin circulating in blood, usually to help evaluate blood sugar regulation, insulin resistance, and the cause of abnormal glucose results.

Quick summary

["This blood test measures insulin and is most useful when interpreted alongside your glucose level and medical history."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
50507-3
Short code
Insulin sp7 SerPl-aCnc
Synonyms
Insulin sp7 SerPl-aCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
2.6
Ref high
24.9
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83525
SNOMED
413618004
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

This test measures the amount of insulin in serum or plasma. Insulin is a hormone made by the pancreas that helps glucose enter cells for energy.

Why might I need this test?

Your clinician may order it when investigating high or low blood sugar, insulin resistance, diabetes, or unusual weight changes. It is often evaluated together with a glucose test.

How is the test performed?

A blood sample is collected, and the laboratory measures insulin using a laboratory testing method. The sample is usually taken from a vein, although some collection methods use a finger or heel stick.

How do I prepare for the test?

Follow your clinician's instructions. The test may be requested after fasting for a set period, and insulin and diabetes medicines can affect the result, so do not change or stop them unless your clinician tells you to.

Reference range

Fasting: 2.6-24.9 μIU/mLN/A

Specimen: serum

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum/Plasma Insulin

Frequently asked questions

Does a high insulin level always mean I have diabetes?
No. Insulin can be elevated for several reasons, including insulin resistance, recent food intake, or certain medicines. Diabetes is diagnosed using blood glucose and other accepted testing information.
Why is my insulin result checked with glucose?
Insulin and glucose show different parts of blood sugar regulation. Comparing them can help your clinician understand whether insulin and glucose levels are appropriately related.
Does the test measure C-peptide?
No. An insulin test measures insulin itself. C-peptide is a separate laboratory test that may sometimes be ordered to assess the body's own insulin production.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy