C-peptide, serum/plasma (quantitative)
This test measures the amount of C-peptide, a small protein produced along with insulin when your pancreas releases it to regulate blood sugar. It helps assess how much insulin your body naturally makes.
["C-peptide helps evaluate insulin production and diabetes management."]
Key facts at a glance
- LOINC
- 25581-0
- Short code
- C peptide sp8 p chal SerPl-sCnc
- Synonyms
- C peptide sp8 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 check if your pancreas is producing enough insulin, especially in people with diabetes or those suspected of having insulin-dependent conditions. It can also help distinguish between types of diabetes or rule out other causes of high or low blood sugar.
What to Expect Before the Test
No special preparation is needed. You may have a small needle inserted into your arm or vein to draw a blood sample. If fasting is required (sometimes for related tests), follow your healthcare provider’s instructions.
How the Test Works
Blood is collected and sent to a lab where it is analyzed to measure the concentration of C-peptide. The test detects the protein naturally produced by your pancreas, independent of insulin levels.
Possible Results and Their Meaning
Results can help determine if your body produces insulin normally or if there’s a defect in insulin production. Low levels may suggest insulin deficiency, while normal or high levels can indicate healthy insulin secretion or other conditions affecting blood sugar.
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 are critical for diagnosing diabetes types (e.g., Type 1 vs. Type 2), assessing insulin-dependent disorders, and monitoring treatment effectiveness. It can also help identify conditions like pancreatic diseases or insulin resistance that affect blood sugar regulation.
Short name
C-peptide Level
Frequently asked questions
How long does it take to get my C-peptide test results?
Can fasting affect my C-peptide test results?
What if my C-peptide test is abnormal?
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