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Insulin, Substance Concentration (Serum/Plasma)

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

This test measures the amount of insulin in your blood, which helps regulate blood sugar levels. Insulin is a hormone produced by your pancreas.

Quick summary

["Insulin levels help diagnose and monitor conditions like diabetes or insulin resistance."]

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

Key facts at a glance

LOINC
55494-9
Short code
Insulin 5M p Glc IV SerPl-sCnc
Synonyms
Insulin 5M p Glc IV SerPl-sCnc
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
2.6
Ref high
24.9
Fasting
true
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

Why Is This Test Done?

Your doctor may order this test to check for diabetes, insulin resistance, or other metabolic disorders. It can also help evaluate symptoms like unexplained weight changes, fatigue, or recurring infections.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a glucose tolerance or fasting panel. Bring any medications you’re taking.

How the Test Is Performed

A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause long-lasting discomfort.

What the Results Mean

Results are interpreted based on your symptoms, medical history, and other tests. Abnormally high or low levels may signal conditions like diabetes, hypoglycemia, or pancreatic issues.

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.

Clinical Significance: Insulin levels are critical for diagnosing diabetes (both type 1 and type 2), insulinoma (a rare tumor causing excessive insulin), or reactive hypoglycemia. Low levels may indicate inadequate insulin production or absorption, while high levels can signal overproduction or resistance.

Short name

Insulin Level

Frequently asked questions

When might my insulin levels be checked?
Your doctor may recommend this test if you have symptoms like unexplained weight loss, frequent urination, extreme thirst, or fatigue. It’s also part of routine screening for diabetes or gestational diabetes during pregnancy.
What does a ‘normal’ insulin level mean?
There’s no single ‘normal’ range because it varies by age, health, and whether you’re fasting. Your doctor will compare your results to your specific situation, such as fasting vs. non-fasting or pre- or post-meal levels.
Can diet or exercise affect insulin levels?
Yes! Eating a meal can temporarily spike insulin levels, while physical activity may lower them. Fasting or avoiding sugar-rich foods can help provide clearer results if your doctor orders a fasting insulin test.
  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