DPP4 and Parkinson disease: Two studies by Svenningsson et al. and Brauer et al. found a reduced incidence of PD among patients receiving DPP4 inhibitors, with an adjusted odds ratio of 0.23 (95% CI 0.07–0.074) and an adjusted incidence rate ratio of 0.64 (95% CI 0.43–0.88), respectively17,18.