KLK3 and type 2 diabetes mellitus: With DM, the actual prostate size and circulating prostate-specific antigen (PSA) are affected [22,23]. A study from Iraq showed that the mean total PSA was lower among T2DM versus non-T2DM males (1.97 ± 1.05 ng/ml versus 2.60 ± 1.22 ng/ml, respectively, p = 0.001) [24].