Determination of C-peptide in children: when is it useful?

Diabetes results from insulin deficiency but despite this endogenous insulin secretion is infrequently measured. C-peptide is not present in synthetic insulin so it's presence indicates endogenous secretion. One of the key roles for measuring C-peptide in childhood is to assist in the diagnosis of diabetes subtypes, which in turn determines appropriate management. It is also useful in Type 1 diabetes to monitor disease course, both in clinical practice and in trials following intervention with disease modifying agents. Measuring C-peptide routinely in Type 1 diabetes provides valuable information to the patient and clinician about glucose variability, risk of hypoglycemia and ketoacidosis. Newer more practical methods of C-peptide determination are now available to allow assessment of endogenous insulin secretion in routine clinical practice. We review the physiology of insulin secretion, the essential roles and methods for C-peptide determination in blood and in urine.