Main idea: the recent study proves a connection between type 2 diabetes and Parkinson’s disease progression on genetic and behavioral levels.
Type 2 diabetes (T2DM) and Parkinson’s disease (PD) are prevalent diseases that affect an aging population. Previous systematic reviews and meta-analyses have explored the relationship between diabetes and the risk of PD, but the results have been conflicting. The objective was to investigate T2DM as a determinant of PD through a meta-analysis of observational and genetic summary data. A systematic review and meta-analysis of observational studies were undertaken by searching 6 databases. We used Mendelian randomization to investigate the causal effects of genetic liability toward T2DM on PD risk and progression. In the observational part of the study, pooled effect estimates showed that T2DM was associated with an increased risk of PD. Using MR, we found supportive evidence for a causal effect of diabetes on PD risk. There was some evidence of an effect on motor progression but not on cognitive progression, but no effect on cognitive decline. The study was published in the Journal of Clinical Epidemiology, Biomarkers, and Prevention. Using meta-analyses of traditional observational studies and genetic data, we observed convincing evidence for an effect of T2DM on PD risk and new evidence to support a role in PD progression.