Diabetes mellitus, prediabetes and the risk of Parkinson's disease: a systematic review and meta-analysis of 15 cohort studies with 29.9 million participants and 86,345 cases.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational cohort studies
PubMed 37185794 · doi:10.1007/s10654-023-00970-0
What was done
Systematic review and meta-analysis searching PubMed and Embase up to February 6, 2022, for cohort studies assessing diabetes mellitus, prediabetes, and the risk of Parkinson's disease (PD). Eligible studies reported adjusted relative risk (RR) estimates and 95% confidence intervals (CIs). Summary RRs were calculated using a random-effects model, with publication bias evaluated using Egger's test, Begg's test, and funnel plots.
What was found
Fifteen cohort studies encompassing 29.9 million participants and 86,345 PD cases were analyzed: - Diabetes vs. no diabetes: summary RR 1.27 (95% CI: 1.20–1.35, I² = 82%). - Prediabetes vs. normal blood glucose: summary RR 1.04 (95% CI: 1.02–1.07, I² = 0%, n = 2). - Diabetes with complications: RR 1.54 (95% CI: 1.32–1.80, n = 3) versus diabetes without complications: RR 1.26 (95% CI: 1.16–1.38, n = 3; p for heterogeneity = 0.18). - No publication bias was detected (Egger's p = 0.41, Begg's p = 0.99).
Why it matters
This large synthesis demonstrates a modest but robust positive association between dysglycemia and the risk of developing Parkinson's disease.
Limits
Substantial heterogeneity was present for the main diabetes analysis (I² = 82%). The prediabetes (n = 2) and complications (n = 3) analyses were based on very few studies. Unmeasured confounding inherent to observational cohorts cannot be ruled out, and data on diabetes duration, age of onset, and glycemic control variability were limited.
Cited by
- contradicts Having type 2 diabetes increases the risk of developing Parkinson's disease by 85%.
- supports Type 2 diabetics have approximately a 40% increased risk of developing Parkinson's disease.