ACE2 and diabetes mellitus: Epidemiological studies identified various comorbidities that pose a high risk for COVID-19-related health hazards, including obesity and diabetes mellitus (DM) [57], possibly attributed to the downregulation of ACE2 in DM [58], which is exacerbated by viral binding, and the inflammatory and fibrotic responses induced by TNF-α and transforming growth factor-beta (TGF-β) [59].