341-OR: Association between Age at Diagnosis of Type 2 Diabetes and Subsequent Risk of Dementia and Its Major Subtypes

Objectives: Type 2 diabetes mellitus (T2DM) is recognized as a major contributor to cognitive decline and dementia in older adults but its importance for its contribution according to age at diagnosis of T2DM remains uncertain. We aimed to investigate the association between dementia and its subtypes in relation to the age at diagnosis of T2DM. Research design and methods: In a population cohort study with the Korean National Health Insurance Service data (2012-2014), a total of 612,201 patients with newly diagnosed T2DM were included. Controls were randomly selected from the general population and matched with a 1:2 ratio based on the propensity score. Participants were followed for until December, 2019. Outcomes of interest were all-cause dementia, Alzheimer’s disease (AD) and vascular dementia (VD). The association of T2DM with dementia was stratified by baseline fasting glucose concentration in patients with T2DM. Cox regression was used to study the excess risk of outcomes. Results: During 6.25 years follow-up, dementia developed in 66,186 patients with T2DM compared with 85,358 control subjects. 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 3.30 (3.11-3.50) for all-cause dementia, 4.08 (3.17-5.23) for AD, and 5.86 (3.87-8.88) 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, 1.36 (1.32-1.40) for AD, and 1.99 (1.71-2.31) for VD. When the analyses were stratified by fasting glucose concentration, a dose-response association was observed. 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 diabetic patients especially in those with young onset T2DM. Disclosure Y.Kim: None. D.Seo: None. M.Kim: None. Y.Cho: None. S.Ahn: None. S.Hong: None. S.Kim: None.