C-peptide (Serum or Plasma) with High-Performance Liquid Chromatography (HPLC) Quantification
This test measures the amount of C-peptide, a byproduct of insulin production, in your blood. It helps assess how much insulin your pancreas is producing naturally.
["C-peptide helps distinguish between insulin-dependent and insulin-independent diabetes causes."]
Key facts at a glance
- LOINC
- 58511-7
- Short code
- C peptide 3h p Glc SerPl-mCnc
- Synonyms
- C peptide 3h 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
Why Is This Test Done?
Your doctor may order this test to evaluate your pancreas’s insulin production. It’s often used in diagnosing diabetes, especially Type 1 diabetes, where the body doesn’t produce insulin at all. It can also help determine if insulin therapy is working correctly by measuring natural insulin production levels.
What Does a High or Low Level Mean?
A higher-than-normal C-peptide level may suggest your body produces some insulin, possibly indicating Type 2 diabetes or prediabetes. A very low level could mean your pancreas isn’t producing insulin, which is common in Type 1 diabetes. Very low levels may also occur with severe pancreatic damage.
How Is This Test Performed?
A blood sample is taken from a vein, usually in your arm. The sample is then sent to a lab for analysis using high-performance liquid chromatography (HPLC), which separates and measures C-peptide precisely.
What Should You Expect Before the Test?
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a larger insulin study. Avoid smoking or caffeine for 30 minutes before the test.
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.
◆Associated findings1
Short name
C-peptide level
Frequently asked questions
How long does it take to get results from this test?
Can fasting affect C-peptide levels?
Is C-peptide testing 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