XDH and type 2 diabetes mellitus: For example, plasma XOR activity is related to obesity and habitual smoking in the general population [35], vascular endothelial dysfunction assessed by flow-mediated dilation in patients with type 1 diabetes [36], liver dysfunction in T2DM patients [37], the prevalence rate of coronary artery spasm [38], and adverse clinical outcomes in patients with heart failure but with a preserved ejection fraction [39], as well as the requirement for cardiovascular intensive care [40].