In these nested case control studies, gene analysis of the single nucleotide polymorphisms (SNPs), rs1799941, rs6257 and rs6259, coding for circulating SHBG, was performed in men and women with type 2 diabetes and matched with controls, indicating that low levels of SHBG are a strong predictor for the development of type 2 diabetes mellitus. Here, SHBG is linked to diabetes mellitus.