DPP4 and type 2 diabetes mellitus: Although a direct involvement of DPP4 in the modulation of SARS-CoV-2 entry has been denied in a stably transfected human embryonic 293T cell line [16], this computational evidence [13] has raised speculation and questions about whether targeting one of the potential host determinants of virulence with DPP4 inhibitors would be useful in attenuating COVID-19 infection after viral exposure [17,18], especially in patients with T2D, typically depicted by a pathogenic dysregulation of DPP4 expression [19].