Glucose & Diabetes

C-Peptide

Normal range 0.8–3.1 ng/mL (0.26–1.03 nmol/L SI). Specimen: Serum (fasting).

Also known as: connecting peptide.

0.8–3.1 ng/mLReference range

Reference range

Conventionalng/mL

0.83.1

SInmol/L

0.261.03

Specimen	Serum (fasting)
Conventional range	0.8–3.1 ng/mL
SI range	0.26–1.03 nmol/L
Conversion factor	×0.331 (conventional → SI)
Panel	Glucose & Diabetes

Convert any C-Peptide result between units on the unit converter.

What is the normal range for C-Peptide?

The standard teaching reference range for C-Peptide is 0.8–3.1 ng/mL in conventional units, or 0.26–1.03 nmol/L in SI units. This value is measured in serum (fasting).

Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population — always use the range printed on the actual result.

Above the range

Common causes of a high C-Peptide

Type 2 diabetes (insulin resistance)
Insulinoma
Renal failure

Below the range

Common causes of a low C-Peptide

Type 1 diabetes
Exogenous insulin use

At the bedside

Nursing considerations

Distinguishes endogenous insulin (high C-peptide) from injected insulin (low C-peptide).

Study aid

Your notes on C-Peptide

Your notes

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More Glucose & Diabetes tests

Glucose, Fasting70–99 mg/dL Glucose, Random< 140 (non-fasting) mg/dL Hemoglobin A1c (HbA1c)4–5.6 %Oral Glucose Tolerance Test (2-hour)< 140 (normal) mg/dL