Insulin, Serum/Plasma — Substance Concentration
This blood test measures the amount of insulin in serum or plasma. It may be used to evaluate diabetes, insulin resistance, or symptoms related to abnormal insulin levels.
["Insulin testing helps assess how the body regulates blood sugar, usually alongside a glucose test."]
Key facts at a glance
- LOINC
- 25694-1
- Short code
- Insulin sp4 p chal SerPl-sCnc
- Synonyms
- Insulin sp4 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
What is this test?
This test measures insulin, a hormone made by the pancreas that helps glucose enter cells for energy. The result is usually interpreted together with blood glucose levels and your clinical situation.
Why might I need this test?
A clinician may order insulin testing to help evaluate diabetes or insulin resistance, particularly when fasting glucose or other blood sugar results are abnormal. It may also be used when symptoms suggest too much or too little insulin.
How is the test performed?
A blood sample is collected from a vein, and the laboratory measures the insulin concentration in the serum or plasma portion of the sample. The test may be performed as a standalone measurement or as part of a larger glucose evaluation.
How do I prepare for the test?
Follow your clinician's instructions about fasting and medication timing. Eating and recent physical activity can affect insulin levels, so do not fast or stop medicines unless the testing team specifically tells you to do so.
Reference range
Fasting: 2.6-24.9 μIU/mLN/A
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.
Higher insulin levels can occur with insulin resistance, obesity, or diabetes, particularly when glucose is also elevated. Lower levels may occur with prolonged fasting, inadequate calorie intake, or excess insulin. Insulin results should be interpreted with glucose measurements, symptoms, medications, and the clinical context rather than alone.
Short name
Insulin
Frequently asked questions
Is fasting required for an insulin blood test?
Why is insulin measured with glucose?
Do medicines or eating affect the results?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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