Type 2 diabetes mellitus as a determinant factor for the age of Parkinson’s disease onset

Abstract Objective: This study aims to identify whether type 2 diabetes mellitus (T2DM) impacts the age of Parkinson’s disease (PD) onset. Methods: Consecutive people living with PD (PwP) with 2-4 years of disease duration were included and categorized according to the presence of T2DM. A 2:1 ratio randomization from the non-DM sample was performed. T2DM diagnosis was defined by a positive personal history of T2DM recorded in the medical files or reported by the subject, or the use of a hypoglycemic drug for glycemic control. A clinical assessment including the Movement Disorder Society Unified Parkinson’s disease rating scale and the Hoehn and Yahr was performed by a movement disorders specialist. Results: One hundred and twenty-four non-T2DM PwP and 62 PwP with T2DM (PD-DM) were included in the study. No statistically significant differences between groups were found in motor and non-motor scores nor in disease duration. The mean age of the whole sample was 63.4 ± 11.9 years, with a mean PD duration of 3.4 ± 0.8 years. In the PD-DM group, the mean duration of T2DM was 12.4 ± 6.8 years, and T2DM was diagnosed 9.2 ± 6.8 years before the PD onset. The PD-DM group had an older age of PD onset (5.9 ± 1.6 year, p < 0.001). Conclusions: Patients with PD-DM had an older age at PD onset, suggesting a potential T2DM role in delaying the age of disease onset.