DPP4 and type 2 diabetes mellitus: A double-blind, placebo-controlled trial showed that the GLP-1 analogue, Exenatide, may have an effect on reducing PD severity after a prolonged washout period, increasing the possibility of a disease-modifying effect.64 A recent cohort study from the same group reported evidence that patients with T2DM taking certain classes of drugs (GLP-1 receptor agonists and DPP4 inhibitors) were at lower risk of PD than patients taking other oral antidiabetic drugs.65