A retrospective cohort study using the TriNetX global network evaluated whether metformin reduces the risk of Parkinson’s disease (PD) and parkinsonism compared with dipeptidyl peptidase-4 inhibitors (DPP-4i) in patients with type 2 diabetes mellitus (T2DM). Using data from 2005–2025, researchers applied an incident-user design with a 1-year landmark period and propensity score matching, resulting in 75,535 patients in each treatment group. Following the landmark period, participants were followed for a median of 5.2 years, representing 785,564 person-years of observation.
The primary analysis found no significant difference in the risk of developing idiopathic PD or secondary parkinsonism between metformin and DPP-4i users. A 5-year landmark sensitivity analysis yielded similar results, supporting the primary findings. Metformin users experienced lower all-cause mortality than DPP-4i…
