T2DM: type 2 diabetes mellitus; HbA1c: hemoglobin A1c; GLP-1 RA: glucagon-like peptide-1 receptor agonist; QW: weekly; QM: monthly; QD: daily; SGLT2: sodium-glucose co-transporter-2; MACEs: major adverse cardiovascular events; RCTs, randomized controlled trials; FPG, fasting plasma glucose; BMI, body mass index. This evidence concerns the gene GCG and type 2 diabetes mellitus.