FNDC5 and type 2 diabetes mellitus: Multivariate regression analysis to predict ED in T2DM patients found that GAD-7 score was the only most significant predictor for ED (ꞵ = - 1.176, standard error = 0.062, p < 0.001).<h4>Conclusion</h4>The current study had demonstrated that irisin positively correlated with the ArIIEF-5 and serum testosterone but negatively correlated with HbA1c in T2DM men.