We conducted a search of the scientific literature across PubMed, Scopus, and Web of Science databases up to August 2025, using combinations of free-text terms and Boolean operators: (“Parkinson’s disease” OR “parkinsonism”) AND (“glucagon-like peptide-1” OR “GLP-1” OR “GLP-1 receptor agonist” OR “incretin” OR “exenatide” OR “liraglutide” OR “lixisenatide” OR “semaglutide” OR “NLY01” OR “PT320” OR “dual receptor agonist”). This evidence concerns the gene GCG and Parkinson disease.