The main observations highlight (i) a significant decrease in SOD3 in CMDs, most pronounced in T2DM, (ii) a notable elevation of miR-21 in the overall CMD group versus controls, (iii) no substantial changes in CAT levels or miR-30b expression across the study groups, and (iv) negative correlations between SOD3 and miR-21 that became stronger in T2DM. Here, CAT is linked to type 2 diabetes mellitus.