Subsequently, the Metformin Genetics Consortium (https://www.pgrn.org/metgen.html) was formed, and the available sample size was increased to 12,910 patients, with the discovery that an intronic variant altering SLC2A2 (GLUT2) expression levels was associated with glycemic response to metformin.21 These two metformin loci (NPAT/ATM and SLC2A2) are the most robustly replicated pharmacogenetic variants in type 2 diabetes. Here, SLC2A2 is linked to type 2 diabetes mellitus.