C-peptide (Serum or Plasma, Mass Concentration)
This test measures the amount of C-peptide, a small protein produced along with insulin when your pancreas releases it to manage blood sugar levels.
["C-peptide helps doctors assess how well your pancreas is producing insulin naturally."]
Key facts at a glance
- LOINC
- 58500-0
- Short code
- C peptide 15M p Glc SerPl-mCnc
- Synonyms
- C peptide 15M p Glc SerPl-mCnc
- 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
What Is C-Peptide Used For?
C-peptide testing is often used to diagnose and monitor conditions like diabetes, especially when insulin levels alone may not provide enough information. It can also help distinguish between types of diabetes or rule out other causes of high blood sugar.
How Is the Test Performed?
A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab for analysis using a specialized immunoassay method to measure C-peptide levels.
Why Might You Need This Test?
Your doctor may recommend a C-peptide test if you have symptoms of diabetes, unexplained high blood sugar, or if you’re being evaluated for conditions like insulinoma (a rare tumor affecting insulin production). It can also be part of routine monitoring for people with diabetes.
What Do Results Mean?
Results help determine whether your body produces insulin naturally. Low levels may suggest diabetes or insufficient pancreatic function, while normal or high levels can indicate healthy insulin production or other conditions.
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 clinically significant because they provide insight into endogenous insulin secretion. Elevated levels may suggest insulin resistance or overproduction, while low levels often correlate with diabetes or pancreatic dysfunction. This test is particularly useful in differentiating between types of diabetes or assessing pancreatic health in conditions like chronic pancreatitis.
Short name
C-peptide level
Frequently asked questions
Why do some people with diabetes have normal C-peptide levels?
How often should I get a C-peptide test?
Can C-peptide levels change with diet or exercise?
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