While earlier studies had indicated the significant effects of SLC47A1 rs2252281, SLC22A2 rs316019, SLC22A1 rs622342 and SLC47A1 rs2289669 on metformin pharmacokinetics and pharmacodynamics [9, 22], the interrelationship between SLC22A2 rs316019 and SLC47A1 rs2289669 was not linked to insulin resistance in T2DM individuals receiving metformin treatment [18]. Here, SLC22A2 is linked to type 2 diabetes mellitus.