Background: In recently, several large longitudinal population-based studies have shown that the rate of cognitive decline is accelerated in elderly people with diabetes mellitus. But the relation between diabetes and AD is still an area of controversy. The objective of this review was to update the evidence for or against diabetes as a risk factor of AD.
Methods: We searched the literature from their inception to May 2016 without restriction of language. We included all longitudinal population-based studies examining the association between diabetes and risk of AD. The meta-analysis was conducted using Stata software.
Results: A total of 17 studies involving 1,746,777 individuals were included. After pooling these 17 studies, subjects with diabetes had significant higher incidence of AD than those without diabetes (RR: 1.53, 95% CI: 1.42-1.63). When stratified by ethnicity, five cohorts were identified as Eastern populations, twelve were identified as Western populations. The Relative risk of AD in Western populations and Eastern populations were 1.36(1.18-1.53) and 1.62(1.49-1.75).
Conclusion: The risk of AD is higher among people with diabetes than in the general population, especially in Eastern populations. So the necessary treatment measures should be taken in order to decrease the risk of AD.
Keywords: Alzheimer's disease; Diabetes; Meta-analysis.
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