Although a significant difference was detected for irisin level between the GDM-G1 (17.59 μg/mL) and GDM-G2 (26.95 μg/mL) subgroups, our study did not reveal a significant difference between GDM and non-GDM mothers, unlike the results reported previously by Aydin et al. [108] and Fatima et al. [109]. This evidence concerns the gene FNDC5 and gestational diabetes.