NOS3 and type 2 diabetes mellitus: Three small studies investigated NOS3 polymorphisms in relation to different T2DM complications with inconclusive results: a study in Iranian patients observed a protective effect of the eNOS 298T allele against DFU [48], a study in Indian T2DM patients observed no association with the risk for DR [49], while another Indian study observed association with increased risk for DKD [46].