The same pattern was observed for the milk samples from the successive stages of lactation; namely, the colostrum and mature milk irisin levels of GDM mothers were significantly lower than for the non-GDM cohort (GDM: 10.4 ± 4.7 pg/mL: and non-GDM: 57.1 ± 8.3 pg/mL, respectively, and GDM: 15.4 ± 0.4 pg/mL and non-GDM: 56.4 ± 9.6 pg/mL, respectively). This evidence concerns the gene FNDC5 and gestational diabetes.