Based on these aspects, the aim of this study was to compare if higher or smaller FNDC5/ irisin levels are associated with inflammatory and metabolic markers, along with caloric/macronutrient intake, physical fitness and T2DM risk in obese middle- aged men with the absence of overt disease, through a cluster study, and also to correlate all variables analyzed with FNDC5/irisin. Here, FNDC5 is linked to type 2 diabetes mellitus.