Based on all the above, the objective of this study is to evaluate the significance of rs622342 in SLC22A1 along with CYP2C9*2 and *3 alleles with regard to the efficacy of metformin/sulfonylurea combination therapy in 88 Lebanese individuals with T2DM followed over a period of 6 months. This evidence concerns the gene CYP2C9 and type 2 diabetes mellitus.