Skip to content

C-peptide measured by high-performance liquid chromatography (HPLC) in serum/plasma

Published: August 9, 2026Updated: August 16, 2026

This test measures C-peptide, a small protein produced equally with insulin during pancreatic beta-cell activity. It helps assess insulin production and rule out diabetes-related conditions.

Quick summary

["C-peptide helps distinguish between true insulin deficiency and lab artifacts."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
27839-0
Short code
C peptide 4h p chal SerPl-mCnc
Synonyms
C peptide 4h p chal SerPl-mCnc
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
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 pancreatic function, diagnose or monitor diabetes, or investigate symptoms like unexplained weight loss, fatigue, or high blood sugar levels. It’s often used alongside insulin levels to confirm insulin production.

What Does the Test Measure?

C-peptide is a byproduct of insulin production. Unlike insulin, which can be affected by medications or lab processing, C-peptide remains stable in the blood. Elevated levels may indicate overproduction of insulin, while low levels suggest insufficient pancreatic function.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The sample is processed and analyzed using HPLC to measure C-peptide concentration accurately.

What Are Common Results?

Results are reported as mass concentration (picograms per milliliter, pg/mL). Interpretation depends on clinical context, such as whether the test is for diabetes screening or evaluation of insulin production.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: serum

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 HPLC

Frequently asked questions

Your doctor may use this test to confirm diabetes (e.g., distinguishing type 1 vs. type 2) or assess pancreatic health in conditions like autoimmune diabetes or pancreatic diseases. It’s also useful in pregnancy to monitor gestational diabetes.
This test helps rule out insulin-related errors in other glucose tests (e.g., insulin antibodies affecting insulin levels). For example, it can confirm whether low blood sugar is due to true insulin deficiency or lab interference.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on lab processing times. Follow-up with your healthcare provider to discuss findings.
Can I eat or drink before this test?
No special preparation is needed, but avoid smoking or heavy meals 2 hours before the draw. Hydration is fine, but fasting isn’t required for this test.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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