Peptide fragment analysis (e.g., C-peptide) using mass spectrometry
This test measures a small peptide produced by your pancreas during insulin production. It helps assess how well your pancreas is making insulin and can be useful in diagnosing or monitoring conditions like diabetes.
["C-peptide helps distinguish between natural insulin production and insulin from injections."]
Key facts at a glance
- LOINC
- 25582-8
- Short code
- C peptide sp9 p chal SerPl-sCnc
- Synonyms
- C peptide sp9 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 body produces insulin naturally. It’s often used to confirm diabetes type (Type 1 vs. Type 2) or to monitor how well insulin therapy is working in people with diabetes. It can also help evaluate pancreatic function in other conditions.
What Does the Test Involve?
A blood sample is taken from a vein in your arm. The sample is sent to a lab where it’s analyzed using mass spectrometry to detect and measure peptide fragments, including C-peptide.
How Is the Test Performed?
No special preparation is needed, but you may be asked to fast for a few hours before the test. Your blood will be drawn by a healthcare professional, and the sample is processed to isolate and measure C-peptide levels.
What Are the Results?
Results are typically reported as a concentration of C-peptide in the blood. While reference ranges vary by lab, higher levels may indicate normal insulin production, while very low levels could suggest insulin deficiency or other pancreatic issues.
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 levels play a key role in diabetes diagnosis and management. High levels may indicate Type 2 diabetes with natural insulin production, while low levels can signal Type 1 diabetes or insulin dependency. It’s also useful in research or evaluating pancreatic diseases.
Short name
C-peptide level (serum/plasma)
Frequently asked questions
What causes abnormal C-peptide levels?
How long does it take to get results?
Can I eat or drink before this 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