Association between age at diagnosis of type 2 diabetes and subsequent risk of dementia and its major subtypes

초록

Background: Type 2 diabetes mellitus (T2DM) is recognized as a major contributor to cognitive decline and dementia in older adults but its importance for younger age at onset of T2DM remains uncertain. Methods: In a population based cohort study with the Korean National Health Insurance Service data, a total of 612,201 patients with newly diagnosed T2DM were included during 2012-2014. Controls were randomly selected from the general population and matched with a 1:2 ratio based on the propensity score. Participants were followed up to December, 2019. Outcomes of interest were all-cause dementia, Alzheimer’s disease (AD) and vascular dementia (VD). Cox regression analysis was used to study the excess risk of outcomes in T2DM in comparison to matched controls, stratified by the age at diagnosis of T2DM. Results: Patients with T2DM diagnosed at ≤50 years had the highest excess risk for most outcomes relative to control with hazard ratio (HR) (95% CI) of 3.29 (3.11-3.49) for all-cause dementia, 4.08 (3.18-5.24) for AD, and 5.82 (3.84-8.81) for VD. All risks attenuated progressively with each increasing decade at diagnostic age but remained significant; for T2DM diagnosed at ≥80 years, the HR (95% CI) was 1.38 (1.34-1.41) for all-cause dementia, 1.35 (1.31-1.40) for AD, and 1.98 (1.70-2.30) for VD. Conclusion: In this population-based cohort study, younger age at diagnosis of T2DM was associated with a higher risk of risk of both AD and VD. Physicians should closely monitor cognitive function in patients with T2DM especially in those with a younger age of onset.