C-peptide (Serum/plasma, mass concentration)
This test measures the amount of C-peptide in your blood. C-peptide is a natural substance produced by your pancreas along with insulin.
["C-peptide helps doctors assess how well your pancreas is producing insulin naturally."]
Key facts at a glance
- LOINC
- 13861-0
- Short code
- C peptide 5M p 1 mg Gc IV SerPl-mCnc
- Synonyms
- C peptide 5M p 1 mg Gc IV SerPl-mCnc
- 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 doctor may order a C-peptide test to evaluate your pancreas’s function, especially if you have diabetes or suspect diabetes. It can also help distinguish between types of diabetes or check if insulin therapy is working properly by measuring your body’s natural insulin production.
What to Expect During the Test
A small blood sample is taken from a vein, usually in your arm. You may feel a slight pinch, but it’s quick and not painful. No special preparation is needed unless your doctor instructs otherwise.
How the Results Are Used
High levels of C-peptide may indicate your body produces insulin naturally, while low levels could suggest insulin deficiency or other pancreatic issues. Your doctor will interpret results in the context of your symptoms and medical history.
Common Reasons for Testing
C-peptide testing is often done to diagnose or monitor diabetes, assess insulin resistance, or evaluate pancreatic health before or after treatments like insulin therapy.
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 biomarker for insulin production. It helps differentiate between type 1 diabetes (where the pancreas produces little to no insulin) and type 2 diabetes (where insulin production may still occur but is insufficient). It’s also useful in assessing whether insulin therapy is effective by measuring endogenous insulin levels.
Short name
C-peptide level
Frequently asked questions
What does a high C-peptide level mean?
What does a low C-peptide level mean?
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