First, this study was designed specifically to evaluate the impact of COPD on circulating levels of MOTS-c and Romo1 in a group of carefully selected and well-characterized patients without comorbidities (other than T2DM and asymptomatic coronary diseases) that might influence the results and a matched for current smoking control group of smokers without COPD (in order to avoid smoking as a potential confounding factor). This evidence concerns the gene MT-RNR1 and coronary artery disorder.