BDNF and major depressive disorder: Furthermore, after adjustment the presence or absence risk factors for depression including gender, HbA1c, BMI , BUN(μmol/l), Cr(μmol/l) and numbers of complications, BDNF Val/Met genotype distributions (OR = 2.105, p < 0.05) and decreased serum levels of BDNF (OR = 0.835, p < 0.01) were also independently associated with depression in T2DM (Table 6).