In fact, a variant in the GLP1R gene (rs6923761; p.Gly168Ser) was found to be associated with a smaller reduction in HbA1c (by 3.0 mmol/mol [0.27%] per A allele) in individuals with type 2 diabetes treated with sitagliptin, vildagliptin or linagliptin for 6 months [14]. This evidence concerns the gene GLP1R and type 2 diabetes mellitus.