REN and diabetes mellitus: These findings can be explained by the changes in the immune system and renin–angiotensin–aldosterone system, together with inflammation, oxidative stress, and endothelial dysfunction in diabetes which have the potential to exaggerate the response triggered by SARS-CoV-2 driving one or more of the cellular processes that result in pulmonary thrombosis, increased vascular permeability and/or cytokine storm, resulting in respiratory failure [20].