In a comparative study evaluating the effects of metformin and insulin (INS) on health parameters in GDM, significant differences were observed [24], and the study found changes in the composition of gut microbiota in the MET group, including a decrease in Firmicutes and Peptostreptococcaceae, and an increase in Proteobacteria and Enterobacteriaceae. This evidence concerns the gene INS and gestational diabetes.