C-peptide (Serum) – Quantitative
This test measures the amount of C-peptide, a natural byproduct of insulin production, in your blood. It helps assess how well your pancreas is making insulin.
["C-peptide helps diagnose and monitor diabetes and pancreatic function."]
Key facts at a glance
- LOINC
- 47584-8
- Short code
- C peptide 10M p Glc SerPl-sCnc
- Synonyms
- C peptide 10M p Glc SerPl-sCnc
- Category
- glucose
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- true
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85610
- SNOMED
- 396252006
- 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 This Test Is Done
Your doctor may order a C-peptide test to check if your pancreas is producing enough insulin. It’s often used to diagnose type 1 or type 2 diabetes, rule out insulin resistance, or evaluate how well insulin therapy is working. It can also help distinguish between diabetes caused by low insulin production versus insulin resistance.
How the Test Works
A small blood sample is taken from a vein in your arm. The sample is sent to a lab, where it’s analyzed using an immunoassay method to measure C-peptide levels. This test does not require fasting unless specified by your doctor.
What to Expect Before the Test
No special preparation is needed for this test, but you may be asked to avoid certain medications or supplements that could affect results. If you’re on insulin or diabetes medications, let your doctor know before the test.
What the Results Mean
C-peptide levels can vary based on your health, diet, and medical conditions. High levels may indicate overproduction of insulin, while low levels suggest insufficient insulin production. Your doctor will interpret the results in the context of your overall health and medical history.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
C-peptide testing is critical for diagnosing diabetes, particularly type 1 diabetes, where the pancreas produces little to no insulin. It can also help monitor insulin therapy effectiveness, assess pancreatic function in non-diabetic individuals, and differentiate between diabetes caused by insulin deficiency versus insulin resistance. Abnormal levels may signal underlying conditions like pancreatic tumors or autoimmune diseases.
Short name
C-peptide level
Frequently asked questions
What causes C-peptide levels to be checked?
How long does it take to get the results?
Can diet or medications affect C-peptide levels?
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