C-peptide measured by high-performance liquid chromatography (HPLC) in serum/plasma
This test checks the amount of C-peptide, a small protein produced along with insulin in your pancreas. It helps assess how well your pancreas is producing insulin naturally.
["C-peptide helps evaluate insulin production and diabetes management."]
Key facts at a glance
- LOINC
- 47590-5
- Short code
- C peptide 3h p Glc SerPl-sCnc
- Synonyms
- C peptide 3h 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?
Doctors may order this test to diagnose or monitor type 1 or type 2 diabetes, especially when insulin levels alone aren’t sufficient for diagnosis. It’s also used to check how well insulin is working in people with diabetes who take insulin therapy. Sometimes, it helps determine if a person has insulin-producing cells still functioning, even if their blood sugar is high.
How Is the Sample Collected?
A blood sample is taken from a vein, usually in your arm. The blood is placed in a special tube and sent to a lab for analysis using HPLC, a precise method that separates and measures C-peptide.
What Does the Result Mean?
Results aren’t given in a simple range because C-peptide levels vary based on diet, activity, and health. Your doctor will compare your result to your medical history and other tests to understand its meaning. High levels might indicate healthy insulin production, while low levels could suggest diabetes or poor insulin function.
Common Reasons for Testing
This test is often used in people with diabetes to confirm diagnosis, assess insulin production, or evaluate treatment effectiveness. It may also be used in research or specialized cases where insulin levels alone aren’t enough to tell the story.
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. Elevated levels suggest normal or excessive insulin production, while low levels may indicate insulin deficiency, such as in diabetes. It’s particularly useful in distinguishing between type 1 and type 2 diabetes, as well as assessing residual beta-cell function in people with long-standing diabetes.
Short name
C-peptide (HPLC)
Frequently asked questions
What does a C-peptide test measure?
Can I eat or drink before this test?
Is this test painful?
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