Several studies have highlighted the importance of bile acid modification genes in the gut microbiome in host metabolic status by quantifying the abundance of bile salt hydrogenase (BSH) gene, 7 alpha-dehydroxylase (ADH) gene, and 7-alpha hydroxysteroid dehydrogenase (HSDH) gene in fecal samples from T2DM patients. This evidence concerns the gene AVP and type 2 diabetes mellitus.