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Insulin, Serum/Plasma — Analyte Concentration

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

Measures insulin levels in a blood sample to help assess how the body regulates blood sugar.

Quick summary

["Insulin testing can help evaluate abnormal blood sugar, but results are best interpreted together with glucose and other tests."]

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

Key facts at a glance

LOINC
50506-5
Short code
Insulin sp6 SerPl-aCnc
Synonyms
Insulin sp6 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?

A clinician may order this test when evaluating diabetes, low blood sugar, unexplained weight changes, or symptoms that could result from too much or too little insulin. It may also be used in specific tests of pancreatic function.

How is the test performed?

A blood sample is collected, and the insulin level is measured using a laboratory assay. The result is reported as a concentration in the blood.

How do I prepare for the test?

Follow the instructions provided by your clinician. Fasting may be requested in some situations, and the timing of the test may be important. Do not stop diabetes medicines or other medications unless your clinician tells you to do so.

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 a normal insulin result rule out diabetes?
No. Insulin changes after eating and varies with blood glucose, stress, medications, and other factors. Glucose and other diabetes tests are usually interpreted alongside insulin.
Do I need to fast for an insulin test?
It depends on the reason the test was ordered. Your clinician or the laboratory should provide specific instructions, especially if the result will be compared with a glucose level.
Why are insulin and C-peptide often checked together?
C-peptide helps show how much insulin the pancreas is producing, while the insulin test measures insulin already circulating in the blood. Together, they can help distinguish different causes of high or low insulin levels.
  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