GLP1R and type 2 diabetes mellitus: In support of this view, PD-associated risk variants have been found associated with monocytes and the innate immune system,13,26,48 in addition to lymphocytes, mesendoderm, liver- and fat-cells.49 Recent work has also demonstrated a causal relationship between BMI and PD,50 which together with the re-purposing of exenatide (a glucagon-like peptide-1 receptor agonist currently licensed for the treatment of type 2 diabetes) for the potential treatment of PD,51 highlights the need to look beyond the brain and selective neuronal vulnerability.