C-peptide (Serum) – Quantitative Measurement
This test measures the amount of C-peptide in your blood. C-peptide is a natural substance produced by your pancreas along with insulin during digestion.
["C-peptide helps assess how well your pancreas produces insulin naturally."]
Key facts at a glance
- LOINC
- 58507-5
- Short code
- C peptide 2M p 1 mg Glc IV SerPl-sCnc
- Synonyms
- C peptide 2M p 1 mg Glc IV 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 doctor may order a C-peptide test to evaluate your pancreas’s ability to produce insulin, especially if you have diabetes or suspect diabetes. It can also help distinguish between types of diabetes or check for insulin-producing tumors.
What to Expect Before the Test
No special preparation is needed. You may have blood drawn from a vein in your arm, similar to other blood tests. If you’re on blood thinners, let your doctor know before the test.
What the Results Mean
C-peptide levels can indicate whether your body produces insulin independently or relies on external sources. Low levels may suggest insulin dependence, while normal or high levels may reflect natural insulin production.
Common Reasons for Testing
Doctors use C-peptide testing to diagnose diabetes types, monitor insulin production in diabetes management, or investigate symptoms like unexplained weight loss or fatigue that might point to 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 is a biomarker for insulin secretion. It helps differentiate between type 1 diabetes (where the pancreas produces little to no insulin) and type 2 diabetes (where insulin production is impaired but not completely absent). It’s also useful in evaluating pancreatic function in non-diabetic individuals or those with suspected endocrine disorders.
Short name
C-peptide level
Frequently asked questions
Why might my doctor recommend this test?
What does a low or high C-peptide level mean?
Can fasting affect C-peptide 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