Research progress of metformin in gestational diabetes mellitus: a narrative review

Gestational diabetes mellitus (GDM) refers to abnormal glucose metabolism that occurs during pregnancy, where blood glucose does not reach the level of overt diabetes during pregnancy. Poor blood glucose control in GDM patients can pose a serious threat to pregnant women and their fetuses by giving rise to adverse pregnancy outcomes for mothers and infants. In 2015, the International Federation of Gynecology and Obstetrics (FIGO) recommended that insulin and metformin be used as the first-line medications for patients with GDM who did not reach the ideal blood glucose level following lifestyle interventions. Recent research has also highlighted the clinical value of metformin with its application for polycystic ovary syndrome (PCOS) treatment, reducing GDM and gestational hypertension syndrome risk along with miscarriage rate in early pregnancy; however, there is no clear consensus regarding the efficacy of metformin treatment in pregnant women with GDM pertaining to its effects on fetal malformation, long-term growth and development of offspring, blood glucose in pregnant women, and maternal and infant outcomes. Therefore, to further understand the safety and efficacy of metformin in the treatment of GDM will provide theoretical basis for the choice of reasonable drugs and the observation the disease trends and outcomes. This review summarizes the most recent literature on safety and efficacy of metformin treatment in GDM. Meanwhile, the effect of metformin on the incidence of GDM in pregnant women with PCOS is also discussed.