C-peptide is a polypeptide chain derived from the breakdown of pro-insulin. Both insulin and C-peptide are released into portal circulation in equimolar amounts. In other words, any insulin the body produces will be reflected in the C-peptide level, therefore, the C-peptide test can be used to monitor beta cell activity and capability over time to help determine when to begin insulin treatment. This test is also used to help diagnose the cause of hypoglycemia and to monitor its treatment. C-peptide measurements are also of value in insulinomas and following post pancreatectomy. HIGH levels of C-peptide generally indicate high levels of endogenous insulin production, and are also seen with insulinomas, hypokalemia, Cushing’s syndrome, or renal failure. LOW levels of C-peptide are associated with low levels of insulin production.
Patient should be fasting. Separate serum and freeze immediately at -20°C. Transfer specimen to plastic transport tube before freezing. Do not thaw & refreeze. State glucose level at the time of sample collection