C-Peptide (C-Pep)
Produced equally with insulin by the pancreas. Distinguishes Type 1 from Type 2 diabetes and evaluates insulin production.
Typical normal range
0.5–2.0 nmol/L
If high ↑
Type 2 diabetes, insulin resistance, insulinoma
If low ↓
Type 1 diabetes, insulin therapy reducing endogenous production
What is a normal C-Peptide level?
A typical reference range is 0.5–2.0 nmol/L. Ranges vary between laboratories and can depend on age and sex, so compare your result with the range printed on your own report.
What does a high C-Peptide level mean?
Type 2 diabetes, insulin resistance, insulinoma. A single result rarely gives a diagnosis on its own; your doctor will interpret it alongside your symptoms and other tests.
What does a low C-Peptide level mean?
Type 1 diabetes, insulin therapy reducing endogenous production. Your doctor will interpret it alongside your symptoms and other tests.
About the Diabetes Markers
These tests show how well your body controls blood sugar. They are used to screen for prediabetes and diabetes, and to monitor treatment over time.
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Medical disclaimer: Reference ranges vary by laboratory, age, sex, and clinical context. This page is for educational purposes only and is not a diagnosis. Always discuss your results with a qualified healthcare professional.