In the study by Zheng et al. [185], two IRS1 variants (rs7578326 and rs2943641) were tested for their associations with insulin resistance, T2D, and MetS, as well as their interactions with diet in two populations of different ancestries: the first one (Genetics of Lipid Lowering Drugs and Diet Network—GOLDN) composed of 820 subjects, all of European descent, and the second one (Boston Puerto Rican Health Study—BPRHS) composed of 844 participants mostly of European descent (57.4%) and for the remaining parts African (27.4%) and Native American (15.4%). This evidence concerns the gene IRS1 and metabolic syndrome.