BDNF and type 2 diabetes mellitus: ANCOVA models adjusting for age, sex, and APOE ɛ4 carrier status revealed that older adults with T2DM did not show reduced BDNF levels relative to those without T2DM (M = 0.17, SD = 0.40 versus M = 0.28, SD = 0.39; F = 2.73, p = 0.099).