BDNF and type 2 diabetes mellitus: Secondly, physical training, which has been associated with high serum BDNF levels in humans [43], results in BDNF overexpression by the endothelium of both peripheral [44] and cerebral vessels [21] in rodents, while hypertension [44] and type 2 diabetes [45] are associated with decreased BDNF expression in peripheral and cerebral endothelium, respectively.