C-peptide (Serum or Plasma, Quantitative)
This test measures the amount of C-peptide, a small protein produced along with insulin when your pancreas releases it to help regulate blood sugar levels.
["C-peptide helps doctors assess insulin production and diagnose diabetes or other pancreatic conditions."]
Key facts at a glance
- LOINC
- 77611-2
- Short code
- C peptide 4h p chal SerPl-sCnc
- Synonyms
- C peptide 4h 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?
C-peptide is a natural byproduct of insulin production. Unlike insulin, which is cleared quickly from the body, C-peptide remains in the bloodstream for a longer time. This test measures its concentration to evaluate how much insulin your pancreas is producing naturally.
Why might your doctor order this test?
Your doctor may request a C-peptide test to diagnose diabetes, monitor insulin production in people with diabetes, or investigate symptoms like unexplained weight loss, fatigue, or digestive issues that could indicate pancreatic problems.
How is the 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 the C-peptide concentration in your serum or plasma.
What does a C-peptide test tell you?
A high C-peptide level may suggest your body produces insulin naturally, while a low level could indicate insufficient insulin production or other pancreatic disorders. This information helps guide treatment plans for diabetes or related conditions.
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 testing plays a key role in distinguishing between types of diabetes, assessing insulin deficiency, and evaluating pancreatic function. It can also help differentiate between diabetes caused by insulin resistance and diabetes caused by insufficient insulin production (e.g., type 1 diabetes).
Short name
C-peptide level
Frequently asked questions
What does a C-peptide test measure?
How long does it take to get results?
Can lifestyle changes 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