In this study, we aimed to determine whether T2D, in people with otherwise apparently normal lipid profiles, may impair HDL protective function of endothelial cells as assessed by ability of HDL to stimulate eNOS Ser1177 phosphorylation and/or inhibit TNF-α dependent NF-κB activation, and thus contribute to endothelial dysfunction associated with T2D. This evidence concerns the gene NOS3 and type 2 diabetes mellitus.