Thus, in the present study, we evaluated the following: (1) whether the mitochondrial fusion/fission mechanisms along with oxidative stress markers, that include reactive oxygen species (ROS) and lipid peroxidation, as well as antioxidant defenses, mediated by glutathione (GSH), catalase, and superoxide dismutase (SOD) were altered in EAT compared to SAT; (2) the potential impact of DM and CAD on the described mitochondrial mechanisms comparing the two adipose tissues, and finally (3) how DM and CAD may influence mitochondrial dynamics in EAT, in patients undergoing cardiac surgery. Here, CAT is linked to diabetes mellitus.