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Insulin, Serum or Plasma (Concentration)

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

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

Quick summary

["Insulin levels help diagnose or monitor conditions like diabetes or hypoglycemia."]

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

Key facts at a glance

LOINC
40288-3
Short code
Insulin 30M p chal SerPl-sCnc
Synonyms
Insulin 30M p chal SerPl-sCnc
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

Why Is This Test Done?

Your healthcare provider may order this test to check for diabetes, insulin resistance, or low blood sugar (hypoglycemia). It can also help evaluate symptoms like unexplained weight changes, fatigue, or unusual thirst/urination.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a glucose-insulin profile. Bring your medications and any recent changes in diet or activity to your appointment.

How the Test Is Performed

A blood sample is drawn from a vein, usually in your arm, using a small needle. You may feel a slight pinch, but it’s over quickly. The sample is sent to a lab for analysis.

What the Results Mean

Results are interpreted based on your symptoms, medical history, and other tests. Abnormally high or low levels may signal underlying health issues that need further evaluation.

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

Short name

Insulin Level

Frequently asked questions

How does fasting affect insulin test results?
Fasting can influence insulin levels. If your test is part of a fasting profile (e.g., glucose-insulin), eating or drinking anything other than water may affect accuracy. Follow your provider’s instructions precisely.
What if my insulin level is high?
High insulin levels may indicate insulin resistance, Cushing’s syndrome, or other conditions like pancreatitis or tumors. Your doctor will discuss next steps, such as further testing or lifestyle changes.
Can I take insulin before my blood test?
Yes, but only if your provider approves it. Taking insulin before testing could skew results, especially if your test is for diagnosing hypoglycemia or diabetes. Always confirm with your healthcare team.
  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