It also transpires that 2 coronavirus co-receptors, ACE2 and DPP4, are well-established actors within metabolic and inflammatory pathways, and renal and cardiovascular physiology, and have been front and center in diabetes and metabolic research: ACE2 is a co-receptor for SARS-CoV-2 while DPP4 is a co-receptor for MERS-CoV. Here, DPP4 is linked to diabetes mellitus.