Type 2 Diabetes as a Determinant of Parkinson's Disease Risk and Progression.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational studies combined with Mendelian randomization analysis
PubMed 33682937 · doi:10.1002/mds.28551
What was done
The authors conducted a systematic review and meta-analysis of observational studies across six databases to evaluate the association between type 2 diabetes mellitus (T2DM) and Parkinson's disease (PD) risk and progression. They also performed Mendelian randomization (MR) using genome-wide association study (GWAS) summary statistics to assess causal effects of genetic liability to T2DM on PD risk and progression.
What was found
In the observational meta-analysis, T2DM was associated with an increased risk of PD (odds ratio [OR] 1.21, 95% CI 1.07-1.36), faster progression of motor symptoms (standardized mean difference [SMD] 0.55, 95% CI 0.39-0.72), and faster cognitive decline (SMD -0.92, 95% CI -1.50 to -0.34). In Mendelian randomization, genetic liability toward T2DM was causally associated with PD risk (inverse-variance weighted [IVW] OR 1.08, 95% CI 1.02-1.14; P = 0.010) and motor progression (IVW OR 1.10, 95% CI 1.01-1.20; P = 0.032), but not cognitive progression.
Why it matters
Combining observational meta-analysis with genetic instrumental variable methods provides converging evidence that type 2 diabetes plays a causal role in both Parkinson's disease susceptibility and the rate of motor symptom progression.
Limits
The abstract does not report the total number of included studies or aggregate sample sizes. Observational associations with cognitive decline were not replicated in the Mendelian randomization analysis. Residual confounding in observational studies and potential horizontal pleiotropy in genetic instruments cannot be ruled out from the abstract data.
Cited by
- partial Having type 2 diabetes increases the risk of developing Parkinson's disease by 40%.