Numerous recently published studies in both humans [11] and rodents [12] have analyzed the association between the changes in the intestinal microbial community induced by increased dietary fiber with the differential production of short-chain fatty acids (SCFAs)—primarily butyrate, propionate, and acetate—and the release of gastrointestinal hormones GLP-1 and PYY (peptide YY), involved in metabolic health and protecting against obesity and diabetes, although the underlying mechanisms are incompletely understood [11,12]. This evidence concerns the gene PYY and diabetes mellitus.