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C-peptide (Serum/Plasma) – Mass Concentration

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

This test measures the amount of C-peptide, a byproduct produced naturally when your pancreas releases insulin. It helps assess how well your pancreas is producing insulin.

Quick summary

["C-peptide helps evaluate insulin production and diabetes management."]

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

Key facts at a glance

LOINC
56583-8
Short code
C peptide 45M p chal SerPl-mCnc
Synonyms
C peptide 45M 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

What Is C-Peptide Used For?

C-peptide testing is primarily used to diagnose and monitor type 1 and type 2 diabetes. It can also help distinguish between insulin-dependent and insulin-independent diabetes, as well as assess pancreatic function in conditions like pancreatitis or autoimmune disorders.

How Is This Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab for analysis using a specialized immunoassay method to measure C-peptide levels.

Why Might You Need This Test?

Your healthcare provider may order a C-peptide test if you have symptoms of diabetes, unexplained weight loss, or if you’re being evaluated for conditions affecting insulin production or pancreatic health.

What Does a C-Peptide Test Tell You?

High levels of C-peptide may indicate your body naturally produces insulin, which can be useful in diagnosing type 2 diabetes or assessing insulin resistance. Low levels may suggest insufficient insulin production or damage to the pancreas.

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 level

Frequently asked questions

How often will I need this test?
The frequency depends on your health condition. If you have diabetes, your doctor may recommend regular testing to monitor progression or treatment effectiveness. For other conditions, testing may be done once or periodically as advised.
What do my C-peptide results mean?
Results are interpreted by your healthcare provider based on your medical history and symptoms. They’ll discuss whether your levels are normal, low, or high and what that means for your health. No specific ranges are provided here, as they vary by lab and individual health.
Can I prepare for this test?
No special preparation is needed for most C-peptide tests. However, if you’re on certain medications or have a history of blood clotting issues, your doctor may provide specific instructions.
  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