Since metformin works through AMPK activation, which leads to phosphorylation of ACE2 [8], we can consider that theoretically this addition of a phosphate group (PO4 −3) would bring about conformational and functional changes in the ACE2 receptor [9]. This could lead to decreased binding with SARS-CoV-2 RBD due to steric hindrance by the addition of a large sized PO4 −3 molecule.