C-peptide (Serum or Plasma, Quantitative)
This test measures the amount of C-peptide, a small protein produced along with insulin during digestion. It helps assess how much insulin your pancreas is making.
["C-peptide helps evaluate your pancreas’s insulin production and diabetes management."]
Key facts at a glance
- LOINC
- 38425-5
- Short code
- C peptide 2.5h p chal SerPl-sCnc
- Synonyms
- C peptide 2.5h 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
Why is this test done?
Doctors may order a C-peptide test to diagnose or monitor type 1 or type 2 diabetes, check if insulin therapy is working, or evaluate pancreatic function in conditions like pancreatitis or cystic fibrosis.
What does the result mean?
Higher-than-expected levels may suggest overproduction of insulin, while lower-than-expected levels could indicate insufficient insulin production or pancreatic issues. Results are interpreted in the context of your medical history and symptoms.
How is the test performed?
A blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab for analysis using an immunoassay method to measure C-peptide concentration.
What should you prepare for?
No special preparation is needed, but inform your doctor about any medications, including over-the-counter drugs or supplements, that might affect blood tests.
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 is a key marker for insulin production. In diabetes, it helps differentiate between type 1 (where insulin is absent) and type 2 (where insulin may still be produced but insufficiently). It also supports monitoring insulin-dependent therapies and assessing pancreatic health in chronic conditions.
Short name
C-peptide level
Frequently asked questions
What does a low C-peptide level mean?
How often should I get this test?
Can diet or exercise 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