Skip to content

Insulin, Serum/Plasma — Concentration

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

A blood test that measures the amount of insulin in serum or plasma. It is often used with a glucose test to help evaluate blood sugar regulation.

Quick summary

["Insulin testing helps assess how well the body controls blood glucose."]

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

Key facts at a glance

LOINC
33813-7
Short code
Insulin sp14 p chal SerPl-aCnc
Synonyms
Insulin sp14 p chal 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 concentration of insulin in blood. Insulin is a hormone made by the pancreas that helps glucose enter cells for energy.

Why might I need this test?

A clinician may order insulin testing to help evaluate symptoms of high or low blood sugar, monitor diabetes treatment, or investigate conditions involving the pancreas. It is commonly interpreted together with a glucose measurement.

How is the test performed?

A blood sample is collected, and the serum or plasma is analyzed in the laboratory, usually with an immunoassay. The sample is then separated from the blood cells so the insulin level can be measured.

How do I prepare for the test?

Follow your clinician's instructions about timing and food intake. Some insulin tests are performed while fasting or at a specified time after eating, so do not fast unless you have been specifically told to do so. Continue medications as directed unless your clinician advises otherwise.

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

Is the insulin test the same as a glucose test?
No. The glucose test measures sugar in the blood, while the insulin test measures the hormone that helps regulate blood sugar. They are often ordered and interpreted together.
Does this test require fasting?
It depends on why the test was ordered. Some measurements are requested while fasting or at a defined time after a meal, so follow the instructions provided by the ordering clinician.
What can cause an unexpected insulin result?
Recent eating, the time of day, physical stress, illness, and medications such as insulin or certain diabetes medicines can affect the result. Your clinician will interpret it using the test timing and your clinical history.
  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