C-peptide (Serum/Plasma)
This test measures the amount of C-peptide, a small protein produced naturally by your pancreas along with insulin. It helps assess how well your pancreas is producing insulin.
["C-peptide helps evaluate insulin production and diagnose diabetes or pancreatic issues."]
Key facts at a glance
- LOINC
- 58521-6
- Short code
- C peptide sp9 p chal SerPl-mCnc
- Synonyms
- C peptide sp9 p chal 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?
Doctors may order a C-peptide test to check if your pancreas is making enough insulin, especially if you have diabetes or unexplained low blood sugar. It can also help determine if insulin is the cause of symptoms like fatigue or weight loss. Sometimes, it’s used to monitor treatment for conditions like diabetes or pancreatic disorders.
What Does the Test Involve?
A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab for analysis. You may feel a small pinch when the needle is inserted, but it’s quick and shouldn’t cause long-lasting discomfort.
What to Expect Before the Test
No special preparation is needed for this test. You can eat and drink normally before your appointment. If you’re on blood thinners or have a history of bleeding disorders, let your healthcare provider know.
What to Expect After the Test
After the blood is drawn, you may feel a slight bruise or soreness at the site, which should go away quickly. Avoid heavy lifting or strenuous activity for a few hours to prevent bruising.
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.
A C-peptide test is useful for diagnosing type 1 or type 2 diabetes, distinguishing between insulin-dependent and non-insulin-dependent conditions. Low levels may indicate insufficient insulin production, while normal or high levels can help confirm diabetes or rule out other causes of symptoms like hypoglycemia. It’s also important in monitoring pancreatic health and evaluating treatments for diabetes or conditions like pancreatitis.
Short name
C-peptide level
Frequently asked questions
What does a C-peptide test tell me about my diabetes?
How often should I get this test?
Can I eat or drink before the 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