INS and gestational diabetes: Well known as the first-line therapy for type 2 diabetes mellitus (Bailey, 2017), MET, in the area of reproduction and pregnancy, has been frequently used to improve ovulation in the treatment of polycystic ovary syndrome (PCOS) and recommended as an alternative to insulin in women with gestational diabetes mellitus (GDM) (Lazaridou et al., 2017; Lindsay and Loeken, 2017).