Endocrine Abstracts

Background: An estimated 462 million individuals are affected by type 2 diabetes mellitus (T2DM), corresponding to 6.28% of the world’s population. Many epidemiological studies have indicated that T2DM may be a risk factor for neurodegenerative diseases, including Parkinson’s disease (PD). Whilst research suggests there are common molecular mechanisms underlying the conditions, studies investigating the epidemiological association have revealed conflicting results. In this review, we aim to investigate the exposure-risk relationship between T2DM and PD, as well as the effects of T2DM on the risk of developing PD.

Method: A systematic review and meta-analysis of 17 observational studies (n= 32,551,133) was undertaken by searching 3 databases for peer-reviewed articles that included subjects with T2DM and PD vs patients without T2DM and a diagnosis of PD. Outcomes assessed included overall risk of developing PD in T2DM patients, risk of PD in patients with T2DM stratified by sex, and age, effects of T2DM complications on risk of PD, the effect of T2DM exposure duration on the risk of PD and the association between T2DM and motor progression of PD.

Results: The overall association between T2DM and PD was deemed significant logOR=0.47 [95% CI; 0.26, 0.67]. The odds of developing PD were higher in participants with T2DM complications compared to T2DM patients without complications (logOR=0.50 [95% CI; 0.28, 0.71]). T2DM was also associated with more severe motor decline. The odds of PD were not significantly influenced by age, sex, or diabetes duration.

Conclusions: Overall, participants with T2DM were at an increased risk of developing PD compared to those without T2DM. The odds of developing PD were even higher in participants with T2DM complications. With the established association between the two conditions, further research should prioritise identifying the underlying mechanism and exploring potential of repurposing anti-diabetic medications as disease-modifying treatments for PD.