C-peptide measured by high-performance liquid chromatography (HPLC) in serum/plasma
This test checks the amount of C-peptide, a natural substance produced by your pancreas along with insulin, to help assess how well your pancreas is making insulin.
["C-peptide helps evaluate your body’s natural insulin production and function."]
Key facts at a glance
- LOINC
- 58506-7
- Short code
- C peptide 2.5h p Glc SerPl-sCnc
- Synonyms
- C peptide 2.5h 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 This Test Is Done
Doctors may order this test to diagnose or monitor conditions like diabetes, especially type 1 diabetes, where the pancreas may not produce enough insulin. It can also help determine if insulin is being produced at all or if it’s being used properly in people with diabetes or those taking insulin therapy.
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 or fasting study. Bring any medications you’re taking to your appointment.
How the Test Is Performed
A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause pain. The blood sample is then sent to a lab for analysis using HPLC to measure C-peptide levels.
What the Results Mean
Results help doctors understand how well your pancreas is producing insulin. Lower than expected levels may indicate diabetes or insulin deficiency, while normal or high levels can help confirm healthy insulin production.
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 testing is critical for diagnosing diabetes, especially type 1, where insulin production is often absent. It also helps monitor insulin therapy in people with diabetes, ensuring the treatment is working as intended. Additionally, it can be used to differentiate between types of diabetes or to assess pancreatic function in other conditions.
Short name
C-peptide (HPLC)
Frequently asked questions
What does a C-peptide test measure?
Can fasting affect C-peptide results?
Is C-peptide testing the same as checking insulin levels?
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