C-peptide (Serum/Plasma) Concentration
This test measures the amount of C-peptide, a small protein produced along with insulin when your pancreas releases it. It helps assess how well your pancreas is producing insulin naturally.
["C-peptide helps evaluate insulin production and diabetes management."]
Key facts at a glance
- LOINC
- 57647-0
- Short code
- C peptide 3.3h p chal SerPl-sCnc
- Synonyms
- C peptide 3.3h p chal SerPl-sCnc
- Category
- coagulation
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- 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
What Is C-Peptide Used For?
C-peptide is primarily used to distinguish between type 1 and type 2 diabetes. In type 1 diabetes, your body doesn’t produce insulin, so C-peptide levels are usually low or absent. In type 2 diabetes, your body may still produce some insulin, so C-peptide levels can be higher. It also helps monitor insulin production in people with diabetes who take insulin treatments.
How Is This Test Performed?
A blood sample is taken from a vein in your arm. The sample is sent to a lab where it is analyzed using an immunoassay method to measure C-peptide concentration.
Why Might You Need This Test?
Your doctor may order a C-peptide test if you have diabetes symptoms, unexplained low blood sugar, or if you’re being evaluated for diabetes or insulin production issues. It can also help determine if you’re taking too much or too little insulin.
What Does a Low or High C-Peptide Level Mean?
Low C-peptide levels may indicate your body isn’t producing insulin naturally, which is common in type 1 diabetes or severe insulin deficiency. High levels might suggest your pancreas is still producing insulin, often seen in type 2 diabetes or pre-diabetes.
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 and assessing insulin dependency. It helps differentiate between insulin-dependent and insulin-independent diabetes, guiding treatment plans and monitoring long-term health. For people on insulin therapy, C-peptide levels can also help assess whether insulin is being absorbed properly or if there’s an issue with insulin production.
Short name
C-peptide level
Frequently asked questions
How long does it take to get results from this test?
Can I eat or drink before this test?
Is there any risk or discomfort with this test?
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