C-peptide (Serum or Plasma, Mass Concentration)
C-peptide is a small protein produced naturally in your body when insulin is made. Your doctor may order this test to help assess how well your pancreas is producing insulin, especially in people with diabetes or those considering insulin treatment.
["This test helps evaluate insulin production and diabetes management."]
Key facts at a glance
- LOINC
- 1987-7
- Short code
- C peptide Ur-mCnc
- Synonyms
- C peptide Ur-mCnc
- Category
- coagulation
- Sample
- urine
- Container
- Sterile urine container
- 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
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why is this test done?
Doctors may order a C-peptide test to check if your pancreas is making enough insulin. It’s often used to diagnose diabetes, determine if insulin therapy is needed, or monitor how well diabetes is being controlled. Unlike insulin, C-peptide is always present in your blood, even if your insulin levels drop.
How is the test collected?
A small blood sample is taken from a vein, usually in your arm. The blood is sent to a lab for testing. You may feel a slight pinch, but it’s a quick and common procedure.
What does the test measure?
C-peptide measures the amount of this protein in your blood. Higher levels may indicate normal insulin production, while very low levels could suggest the pancreas isn’t making enough insulin.
How is the test used in diabetes care?
C-peptide helps doctors decide if you need insulin or other diabetes medications. It can also help track how well your body responds to treatments over time, especially in people with type 1 or type 2 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 particularly useful for distinguishing between type 1 and type 2 diabetes, as well as evaluating the effectiveness of insulin therapy. It avoids the need for insulin measurements, which can be affected by recent insulin use.
Short name
C-peptide level
Frequently asked questions
Why might my doctor ask for a C-peptide test?
How long does it take to get results?
What if my C-peptide levels are low?
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