C-peptide (Serum or Plasma, Mass Concentration)
This test measures the amount of C-peptide, a small protein produced by your pancreas along with insulin. It helps assess how well your pancreas is producing insulin naturally.
["C-peptide helps diagnose and monitor diabetes and pancreatic function."]
Key facts at a glance
- LOINC
- 58495-3
- Short code
- C peptide 10M p 1 mg Gc IV SerPl-sCnc
- Synonyms
- C peptide 10M p 1 mg Gc IV 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
Why Is This Test Done?
Your healthcare provider may order a C-peptide test to check if your pancreas is making enough insulin. It can also help determine whether insulin is being produced naturally or if you need external insulin treatment. This test is often used in diagnosing type 1 or type 2 diabetes, especially when insulin levels alone may not be sufficient for accurate diagnosis.
How Is the Test Performed?
A blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab for testing. The specimen is either serum or plasma, depending on the lab’s standard procedure.
What Does the Test Result Mean?
C-peptide levels can vary based on your health and medical history. High levels might suggest your pancreas is producing insulin normally, while low levels could indicate insufficient insulin production or other pancreatic issues. Your doctor will interpret the results in the context of your overall health and symptoms.
Common Reasons for Testing
C-peptide testing is commonly used to evaluate diabetes management, rule out insulin resistance, and assess pancreatic function in conditions like pancreatitis or pancreatic cancer.
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.
Clinical Significance: C-peptide plays a critical role in diagnosing and managing diabetes. Unlike insulin, C-peptide is not affected by insulin injections or oral medications, making it a reliable marker for natural insulin production. It helps distinguish between type 1 and type 2 diabetes and guides treatment decisions, such as whether insulin therapy is needed.
Short name
C-peptide level
Frequently asked questions
What happens if my C-peptide levels are low?
Can diet or exercise affect C-peptide levels?
How often should I get 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