The current study aimed to assess the serum level of irisin in T2DM men with erectile dysfunction (ED) compared to T2DM patients with normal erectile function and healthy controls, as well as investigate the association between serum irisin level and the severity of ED in T2DM patients.<h4>Patients and methods</h4>A cross-sectional study was conducted on 90 males, divided into three groups: 32 T2DM patients with ED, 24 T2DM patients without ED, and 34 healthy controls. This evidence concerns the gene FNDC5 and type 2 diabetes mellitus.