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Insulin, Serum/Plasma — Mass Concentration

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

Measures the amount of insulin in a blood sample to help assess glucose regulation, insulin production, and the cause of low or high blood glucose.

Quick summary

["An insulin blood test helps clinicians evaluate how the body regulates glucose and investigate abnormal blood sugar levels."]

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

Key facts at a glance

LOINC
1571-9
Short code
Insulin pre TBM IV SerPl-mCnc
Synonyms
Insulin pre TBM IV SerPl-mCnc
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 serum or plasma. Insulin is a hormone made by the pancreas that helps glucose enter cells for energy and helps keep blood glucose within a healthy range.

Why might I need this test?

Clinicians may order insulin testing when evaluating unexplained low blood glucose, diabetes, insulin resistance, or symptoms that suggest too much or too little insulin. It may also be used as part of a supervised glucose-tolerance or other timed evaluation.

How is the test performed?

A blood sample is drawn and tested in a laboratory to determine the insulin concentration. If several samples are ordered, they may be collected at specific times before and after a meal, glucose challenge, or other procedure.

How do I prepare for the test?

Follow the preparation instructions on your laboratory order, including any required fasting or timing. If timed insulin measurements are requested, report the time of each blood draw and the last meal or glucose dose as directed.

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 fasting required for an insulin test?
It depends on why the test was ordered. Some insulin tests are performed after fasting, while others are timed after eating or receiving glucose, so follow the instructions provided by your clinician.
Does the test diagnose diabetes?
No. Insulin is usually interpreted alongside fasting or standardized glucose tests and other clinical information rather than used by itself to diagnose diabetes.
Why might insulin be measured more than once?
Multiple measurements show how insulin levels change in response to a meal or glucose challenge. The collection times are important when interpreting the results.
  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