Don’t perform routine measurement of C-peptide in diabetes patients.

Type of practice

Laboratory tests

Topic Area


It is not necessary to dose hematic C-peptide for the diagnosis of type 1 and type 2 diabetes . Measurement of the response by C-peptide to glucagon or to mixed meals can help in rare cases in which it is difficult to differentiate the diagnosis between the two types of diabetes. However, in this clinical situation, too, the response to the pharmacological therapy provides useful information, and it is not clinically necessary to identify C-peptide . In rare cases it can be useful to measure C-peptide concentration in order to better phenotype the patient with diabetes and it can be useful in type 1 diabetes for getting the full prognostic picture of complications. C-peptide identification is essential for evaluation of possible hypoglycemia which has been self- caused due to insulin taken for other than therapeutic purposes.


1. Sacks DB, Mark A, Bakris Gl et al. Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus. Diabetes Care 2011; 34: 61-99.
2. Robbins DC, Andersen L, Bowsher R, et al. Report of the American Diabetes Association’s Task Force on standardization of the insulin assay. Diabetes 1996; 45:242–56.
3. AMD-SID. Standard italiani per la cura del diabete mellito 2014.

Attention. Please note that these items are provided only for information and are not intended as a substitute for consultation with a clinician. Patients with any specific questions about the items on this list or their individual situation should consult their clinician.