C-Peptide

Clinical Chemistry

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Description

C-peptide is a 31 amino acid chain produced by pancreatic beta-cells during the enzymatic cleavage of proinsulin to insulin. Although insulin and c-peptide are produced in equimolar concentrations, c-peptide has a longer half-life than insulin. This means that c-peptide is often used as a marker of residual beta-cell function and insulin resistance in patients with diabetes mellitus.

Low levels of c-peptide may be seen when insulin secretion is decreased, such as in type 1 diabetes, or as a normal response to exogenous insulin (please note, that most types of exogenous insulin are not detected with the Roche insulin assay).

High levels of c-peptide may be seen when insulin secretion is increased, such as in type 2 diabetes, insulinomas and oral hypoglycaemic drugs e.g. sulphonylureas. Additionally, as c-peptide is cleared by the kidneys, levels may be increased in renal impairment.

C-peptide measurement may also be used as a marker of endogenous insulin production in insulin-treated patients who have developed anti-insulin antibodies, as these can interfere in the insulin assay.

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Indications

Investigation of hypoglycaemia (patient must be hypoglycaemic at time of sampling for c-peptide/insulin).

Differentiation of Type 1 and Type 2 diabetes mellitus.

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Sample Type

(Usually) fasting specimen; SST/Gel, minimum 2 mL (1 mL separated serum). Freeze aliquot if not being sent to RHH promptly

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Reference Range

Reference ranges are provided on the report. Alternatively, please contact the laboratory for current ranges.

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Turnaround Time

Within 1 week

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Testing Frequency

Weekly

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Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.