Vrieze et al. (2012) reported that infusing microbiota from lean donors to obese male recipients with metabolic syndrome significantly increased their insulin sensitivity. Also, case reports have suggested that intestinal bacteria upon fecal microbiotiota transplantation might affect bodyweight and insulin sensitivity of the recipient (Kootte et al., 2017; De Groot et al., 2019). This evidence concerns the gene INS and metabolic syndrome.