%0 Journal Article
%T Pattern of C-peptide response to oral glucose tolerance test: Interest and cut-off values.
%A Bonnet-Serrano F
%A Abou Jaoude M
%A Laguillier C
%A Gobeaux C
%A Bouzerara A
%A Mosnier-Pudar H
%A Guibourdenche J
%J Ann Endocrinol (Paris)
%V 83
%N 2
%D Apr 2022
%M 35074395
%F 3.117
%R 10.1016/j.ando.2021.12.006
%X <B>OBJECTIVE: </B>The oral glucose tolerance test (OGTT) classifies subjects as normal, glucose intolerant or diabetic depending on glycemia at 120 min (T120) post-test. Five insulin profiles associated with different incidences of diabetes over 10 years' follow-up were previously described following OGTT. However, insulin measurement is sensitive to hemolysis, and can be replaced by C-peptide assay on hemolyzed samples. However, little is known about patterns of C-peptide response to OGTT.<BR><B>METHODS: </B>In total, 128 patients were included, to establish preliminary baseline C-peptide values and to evaluate C-peptide response to OGTT in comparison to insulin response, using the Liaison XL immunoanalyzer.<BR><B>RESULTS: </B>Hundred patients had a normal glycemic response, 19 were classified as glucose intolerant and 9 as diabetic. In normal subjects, median C-peptide values (nmol/L, with 5-95 percentiles) were 0.53 (0.23-1.37) at baseline, peaking at 2.36 (0.94-1.83) at T60, and decreasing to 2.09 (1.13-4.36) at T120. The C-peptide response pattern was similar but flatter than the insulin pattern because of different catabolism pathways. Nevertheless, C-peptide and insulin response profiles were discordant in only 9.4% of cases. Profile 3 (C-peptide peaking at T60) was the most prevalent in normal patients whereas profile 4 (peak at 120 min and lower level at T30 than at T60) was the most prevalent in glucose intolerant and diabetic patients.<BR><B>CONCLUSIONS: </B>In OGTT, C-peptide could replace insulin determination on hemolyzed blood samples to predict the risk of type 2 diabetes.