Since T2DM increases the risk of cognitive decline and development of dementia, and several studies have suggested that lower BDNF levels may be a risk factor of diabetic neurovascular complications, we sought to investigate 1) differences in BDNF levels between those with and without T2DM, and 2) WMH volume, a marker of small vessel cerebrovascular disease, as a moderator on the association of BDNF with both cognition and hippocampal volume in older adults with and without T2DM. This evidence concerns the gene BDNF and type 2 diabetes mellitus.