Results: Compared with those in the comparison group (treatment with a sulfonylurea), patients with a DPP-4 inhibitor cDDD of >150 had a hazard ratio (HR) of 1.30 for PD development (95% confidence interval [CI]: 0.97-1.73; adjusted P = .263); the HRs for patients with a cDDD of <75 or 75–150 were 0.95 (95% CI: 0.71-1.27; adjusted P = .886) and 1.06 (95% CI: 0.75-1.50; adjusted P = .886), respectively. This evidence concerns the gene DPP4 and Parkinson disease.