The present longitudinal study documents for the first time that in leukocytes of women with GDM during and after pregnancy, there are quantitative changes in the expression profiles of several important genes engaged in insulin signaling and glucose transport and, moreover, the mRNA level of one of the investigated genes, i.e., SLC2A4, is inversely correlated with HOMA-IR in the postpartum period. Here, SLC2A4 is linked to gestational diabetes.