SLC22A1 and type 2 diabetes mellitus: Our results showed that there were no significant differences in SLC22A1 rs594709 and SLC47A1 rs2289669 allele frequencies and genotype frequencies between T2DM patients and healthy subjects. SLC22A1 rs594709 A allele carriers showed a better metformin efficacy in insulin sensitivity compared with GG genotype patients. SLC47A1 rs2289669 GG genotype patients showed a better efficacy in improving blood lipid.