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Insulin, Serum/Plasma — Arbitrary/Catalytic Concentration

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

A blood test that measures insulin levels to help evaluate glucose regulation, insulin resistance, and the function of pancreatic beta cells.

Quick summary

["Insulin results are most useful when interpreted with glucose levels, symptoms, medications, and the reason the test was ordered."]

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

Key facts at a glance

LOINC
50502-4
Short code
Insulin sp2 SerPl-aCnc
Synonyms
Insulin sp2 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 a blood sample. 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 an insulin test to investigate high or low blood glucose, insulin resistance, diabetes, or symptoms of excessive or insufficient insulin. It may also be measured as part of a supervised glucose-tolerance test.

How is the test performed?

Blood is collected from a vein and separated into serum or plasma. A laboratory then measures the insulin concentration in the sample using a validated laboratory method.

How do I prepare for the test?

Fasting may be required for some insulin tests, while others must be collected at a specific time after glucose or food. Follow the instructions provided by your clinician and do not change insulin or other diabetes medications 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 a high insulin level mean I have diabetes?
Not necessarily. Elevated insulin can occur with insulin resistance before or alongside type 2 diabetes, but other factors can also affect the result. Your clinician will interpret it with glucose levels and your medical history.
Is this the same as an insulin resistance test?
No. An insulin blood test measures insulin at a particular time, while an insulin resistance test may combine several insulin and glucose measurements to estimate how effectively the body responds to insulin.
Should I fast before this test?
It depends on the test. Some insulin tests require fasting, while others use samples collected at precise times after glucose is given. Confirm the timing and preparation instructions before your appointment.
  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