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Insulin, Serum/Plasma — Substance Concentration

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

Measures insulin in blood to help evaluate how the body regulates blood glucose, especially when diabetes or episodes of low blood sugar are suspected.

Quick summary

["An insulin blood test helps show how well the body is producing and using insulin to control blood glucose."]

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

Key facts at a glance

LOINC
25689-1
Short code
Insulin sp14 p chal SerPl-sCnc
Synonyms
Insulin sp14 p chal SerPl-sCnc
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 blood test measures the amount of insulin, a hormone made by the pancreas, present in serum or plasma. Insulin helps glucose enter cells for energy and helps keep blood glucose within a healthy range.

Why might I need this test?

A clinician may order this test when evaluating diabetes, recurring low blood sugar, or symptoms that may result from abnormal insulin production or insulin resistance. It may also be used to monitor certain diabetes treatments.

How is the test performed?

A blood sample is collected, usually by a vein, and sent to a laboratory. The laboratory measures insulin in the sample, and the result is interpreted together with your blood glucose level, symptoms, medications, and the timing of the test.

How do I prepare for the test?

Follow the preparation instructions provided by your clinician. The test may be ordered while fasting or at a specific time after eating or taking insulin, so do not change your usual medication or meal schedule unless instructed.

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

Insulin

Frequently asked questions

Does this test diagnose diabetes?
Not by itself. Insulin is usually interpreted alongside blood glucose, symptoms, medical history, and sometimes additional laboratory tests.
Do I need to fast before the test?
It depends on why and when the test was ordered. Some measurements are made after an overnight fast, while others are timed after a meal or glucose-containing drink, so follow the instructions you receive.
Why are my insulin and glucose results interpreted together?
Insulin and glucose rise and fall in relation to one another. Comparing them helps the clinician understand how effectively the body is regulating blood glucose.
  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