Clinical use of C-peptide and β-cell specific autoantibodies during gestational diabetes mellitus

Gestational diabetes mellitus (GDM) confers a risk for developing type 2 diabetes later in life, but the risk of developing type 1 diabetes is also increased. In this study we have evaluated the clinical use of C-peptide and β-cell specific autoantibodies during pregnancy with GDM as predictors for later development of diabetes. C-peptide levels were measured 2 hours after glucose intake in pregnancies with GDM during 2006–2008 (n=281). The mother′s age and first weight during pregnancy, birth weight of the newborn and postpartum development of diabetes in the women were noted from their records. Between 1995–2008, 669 women developed GDM and were tested for glutamic acid decarboxylase antibodies (GADA) and tyrosine phosphatase antibodies (IA-2A); 34 women (5%) were found positive for at least one autoantibody. The incidence of diabetes was significantly higher (p<0.001) among women with positive autoantibodies (5/12) compared to women without autoantibodies (21/266) during 2006–2008. When comparing stimulated C-peptide during GDM between women who later developed diabetes and those who did not, there was no significant difference. Among the 34 women who were autoantibody positive during their GDM between 1995–2008, 50% (n=17) had developed type 1 diabetes, and an additional five had impaired fasting glucose or impaired glucose tolerance. In conclusion, stimulated C-peptide values were of no use in women with GDM regarding prediction of future diabetes. Analysis of GAD antibodies during GDM is recommended, due to a high risk of type 1 diabetes after delivery. A structured follow up of all women with GDM ought to be considered. Copyright © 2012 John Wiley & Sons.