C-peptide (Serum or Plasma) Concentration
This blood test measures the amount of C-peptide, a small protein produced along with insulin when your pancreas releases it to manage blood sugar levels. It helps assess how well your pancreas is producing insulin naturally.
["C-peptide helps doctors evaluate insulin production and diagnose conditions like diabetes."]
Key facts at a glance
- LOINC
- 47833-9
- Short code
- C peptide 6M p Gc SerPl-sCnc
- Synonyms
- C peptide 6M p Gc 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?
Your healthcare provider may order a C-peptide test to check if your pancreas is making enough insulin. It can also help diagnose type 1 diabetes, type 2 diabetes, or other conditions affecting insulin production, such as pancreatic diseases. Sometimes, it’s used to monitor treatment effectiveness in people with diabetes.
What Does the Test Involve?
A small blood sample is taken from a vein, usually in your arm. The blood is sent to a lab where it’s analyzed to measure C-peptide levels. No special preparation is usually needed, but you may be asked to fast for a few hours before the test if instructed by your doctor.
What to Expect After the Test
After the blood draw, you may feel a slight pinch or bruising at the site, but it usually goes away quickly. You can resume normal activities right after. Results are typically ready within a few days to a week, depending on the lab.
What Are the Possible Results?
Results are compared to a general range of what’s considered normal for healthy adults, but your specific range may vary based on medical conditions or other factors. High or low levels can signal different health concerns, so it’s important to discuss your results with your doctor.
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 levels can indicate whether your body produces insulin naturally. Low levels may suggest insulin deficiency (e.g., type 1 diabetes), while high levels could point to overproduction or other metabolic issues. It’s also useful in distinguishing between insulin-dependent and insulin-independent diabetes. Your doctor will interpret results in the context of your overall health and symptoms.
Short name
C-peptide
Frequently asked questions
What does a C-peptide test help diagnose?
How does C-peptide differ from insulin?
Can fasting affect C-peptide test results?
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