While a prospective cross-sectional study by Kurek Eken et al. [54] reported that serum Nrg4 levels were significantly elevated in women with GDM compared to healthy subjects, a prospective cohort study by Kralisch et al. [55] reported the opposite outcomes showing that serum Nrg4 levels were low and improved during pregnancy and at the postpartum time point in women with GDM, respectively. This evidence concerns the gene NRG4 and gestational diabetes.