In addition, common anti-diabetic treatments such as dipeptidyl peptidase-4 (DPP4) inhibitors, glucagon-like peptide-1 (GLP-1) agonists and metformin have shown promise in the treatment of PD and cognitive impairment in human and animal models of PD (Ashraghi et al., 2016). The gene discussed is GCG; the disease is Parkinson disease.