Pro-inflammatory cytokines secreted in adipose tissue in GDM (such as TNFα, IL-1β, IL-6) impair insulin signaling and inhibit insulin release from β-cells; however, this relationship is complex and not straightforward, because there are studies reporting that GDM placentae secrete fewer pro-inflammatory cytokines than healthy placentae [12]. This evidence concerns the gene INS and gestational diabetes.