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C-peptide (Quantitative) with High-Performance Liquid Chromatography (HPLC) Measurement

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

This test measures the amount of C-peptide, a small protein produced equally with insulin during digestion of glucose, helping assess pancreatic beta-cell function.

Quick summary

["C-peptide helps evaluate how well your pancreas produces insulin naturally."]

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

Key facts at a glance

LOINC
58503-4
Short code
C peptide 1h p Glc SerPl-mCnc
Synonyms
C peptide 1h 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 healthcare provider may order a C-peptide test to diagnose or monitor conditions like diabetes, pancreatic disorders, or to check if insulin therapy is working properly. It can also help distinguish between types of diabetes or rule out insulin overproduction.

What Does the Test Involve?

A blood sample is taken from a vein, usually in your arm. The sample is processed to measure C-peptide levels using high-performance liquid chromatography (HPLC), a precise method for detecting small proteins.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for a few hours before the test if instructed by your provider. Wear comfortable clothing and bring any medications you’re currently taking.

What Are the Results Typically Used For?

Results help determine whether your pancreas is producing insulin normally. High levels may indicate insulin-producing tumors, while low levels can suggest diabetes or other metabolic issues.

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

What does a high C-peptide level mean?
A high C-peptide level may suggest your body is producing insulin naturally, possibly due to conditions like insulinoma (a rare tumor) or less commonly, certain metabolic disorders.
What does a low C-peptide level mean?
A low C-peptide level often indicates insufficient insulin production, which can be seen in type 1 diabetes or other pancreatic dysfunctions. It may also appear in cases where insulin is being artificially administered.
Is fasting required for this test?
Fasting may be required depending on your healthcare provider’s instructions, but it’s not always mandatory. Always follow their guidance to ensure accurate results.
  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