Synonyms: Connecting Peptide; Insulin C-Peptide; Proinsulin C-Peptide

Why It Is Done

Distinguish between type 1 diabetes and type 2 diabetes.
Determine the cause of low blood sugar (hypoglycemia).
Monitor recovery after the removal of an insulin-producing tumor of the pancreas (insulinoma).

Test Overview

A C-peptide test measures the level of this peptide (an inactive amino acid) that is released in the body in amounts equal to insulin. Insulin helps the body use and control the amount of sugar (glucose) in the blood. Insulin allows glucose to enter body cells, where it is used for energy. The level of C-peptide in the blood can indicate how much insulin is being produced by the pancreas.

How To Prepare

Patient must fast 8 to 12 hours