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. It helps assess how well your pancreas is producing insulin naturally.
["C-peptide helps diagnose and monitor diabetes and pancreatic function."]
Key facts at a glance
- LOINC
- 47583-0
- Short code
- C peptide 1.5h p Glc SerPl-sCnc
- Synonyms
- C peptide 1.5h p Glc SerPl-sCnc
- Category
- glucose
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- true
- 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 evaluate your pancreas’s ability to produce insulin. It’s often used to distinguish between type 1 diabetes (where the pancreas produces little to no insulin) and type 2 diabetes (where the pancreas still produces some insulin). It can also help monitor insulin production in people with diabetes or those taking insulin therapy.
How Is the Sample Collected?
A blood sample is taken from a vein, usually in your arm. The blood is then separated into serum or plasma for testing. You may feel a small pinch when the needle is inserted, but it typically doesn’t cause discomfort afterward.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for a few hours before the test if it’s part of a glucose tolerance test. Always follow your healthcare provider’s instructions.
What the Results Mean
Higher-than-normal levels may indicate overproduction of insulin or certain conditions like insulinoma. Lower-than-normal levels can suggest diabetes, pancreatic issues, or insulin therapy dependence. Your results will be interpreted by a healthcare professional based on your medical history and symptoms.
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, assessing insulin production, and guiding treatment plans. In type 1 diabetes, C-peptide is often undetectable or very low because the pancreas stops producing insulin. In type 2 diabetes, C-peptide levels may be normal or slightly elevated, reflecting some remaining insulin production. It can also help detect pancreatic tumors or other endocrine disorders.
Short name
C-peptide level
Frequently asked questions
How long does it take to get my results?
What does a low C-peptide level mean?
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