Efficacy of metformin in the treatment of parkinsonism and depression among diabetic patients type 2

Abstract

Introduction: Parkinson’s disease (PD) often coexists with type 2 diabetes mellitus (T2DM), which may worsen disease progression. Metformin, a common diabetes medication, showed potential benefits beyond blood sugar control. Objectives: This study examines metformin’s impact on renal function, neurological biomarkers, and clinical outcomes in patients with both PD and T2DM. Patients and Methods: This prospective case-control study involved 50 patients with both T2DM and parkinsonism, recruited from Al-Azhar university hospitals in Assiut, Egypt, between August 2024 and August 2025. Participants were divided equally into two groups; a control group receiving their standard treatment for Parkinsonism and diabetes, and a metformin-treated group receiving metformin alongside their usual therapies. Demographic data and laboratory markers were collected at baseline. Disease assessment employed standardized tools such as the unified Parkinson’s Disease Rating Scale (UPDRS) for motor function, Beck Depression Inventory (BDI) for depression severity, Hoehn and Yahr scale for disease staging, Montreal Cognitive Assessment (MoCA) for cognitive evaluation, and Parkinson’s Disease Questionnaire-39 (PDQ-39) for quality of life (QOL). All assessments were repeated after a 12-month follow-up to analyze changes relative to baseline. Results: The findings indicated that metformin treatment offers comprehensive benefits by protecting against renal function decline, influencing neurological biomarkers, and supporting multiple clinical domains in PD. It appears to mitigate disease progression, preserve cognitive function, and enhance psychosocial well-being, while having neutral effects on vitamin status and potentially positive, though non-significant, effects on inflammatory markers. Overall, metformin not only prevents typical clinical deterioration but also actively improves motor, cognitive, psychological, and quality-of-life outcomes. Conclusion: Metformin demonstrates promising multifaceted benefits in PD patients with T2DM by not only protecting renal function and preventing clinical deterioration but also actively improving motor, cognitive, psychological, and quality-of-life outcomes across multiple clinical domains, supporting its consideration as an adjunctive therapeutic strategy pending further research.