Potential protective link between type I diabetes and Parkinson’s disease risk and progression

Background Epidemiological studies suggested an association between Parkinson’s disease (PD) and type 2 diabetes, but less is known about type 1 diabetes (T1D) and PD. Objectives To explore the association between T1D and PD. Methods We used Mendelian randomization, linkage disequilibrium score regression and transcriptome wide association analysis (TWAS) to examine the association between PD and T1D. Results Mendelian randomization showed a potentially protective role of T1D for PD risk (inverse-variance weighted (IVW); OR (95% CI) 0.97 (0.94-0.99); p=0.039), as well as motor (IVW; 0.94 (0.88-0.99); p=0.044) and cognitive progression (IVW; 1.50 (1.08-2.09); p=0.015). We further found negative genetic correlation between T1D and PD (rg=-0.17, p=0.016), and identified nine genes in cross-tissue TWAS that were associated with both traits. Conclusions Our results suggest a potential genetic link between T1D and PD risk and progression. Larger comprehensive epidemiological and genetic studies are required to validate our findings.