ProNon-obese ACE2 KO mice manifest a mild form of SARS-CoV infection and strongly reduced pathological changes in the lungs compared to their wild-type counterparts. ContraComorbidity of obesity/T2D with severity of COVID-19 was observed in viral infections other than SARS-CoV/CoV-2 and thus is not ACE2 specific. ACE inhibitors (ACEi) and Ang II receptor blockers (ARBs), both inducing the expression of ACE2, are thought to be beneficial in COVID-19. Here, ACE2 is linked to type 2 diabetes mellitus.