INS and type 2 diabetes mellitus: Despite the expectation that selenium might prevent the development of diabetes owing to its antioxidant and insulin-mimetic properties [6,7,8], in recent years, some epidemiological studies, including cross-sectional studies and longitudinal studies, have shown that supranutritional selenium intake or high plasma selenium levels are a possible risk factor for the development of type 2 diabetes or metabolic syndrome [9,10,11,12].