Patients with type 2 diabetes have significantly impaired incretin function (9–12), and treatment with stable GLP-1 receptor agonists (GLP-1RAs) or enhancing endogenous levels of active GLP-1 using dipeptidyl peptidase 4 inhibitors (DPP-4is) effectively lower blood glucose levels (13, 14). The gene discussed is GCG; the disease is type 2 diabetes mellitus.