Dementia risk in people with type 1 diabetes and associated risk factors: a nationwide, register-based cohort study

Objective Life expectancy of individuals with type 1 diabetes has increased, extending exposure to age-related conditions including dementia. Although earlier studies have linked type 1 diabetes with higher dementia risk, the relationships with dementia subtypes and associated risk factors are incompletely understood. Research Design and Methods In this cohort study, 43,440 individuals with type 1 diabetes from the Swedish National Diabetes Register and 217,109 age-, sex- and county matched controls from the Swedish Total Population Register were included. Cox regression was used to study the relation between type 1 diabetes and risk of all-cause dementia and dementia subtypes (Alzheimer’s disease, vascular dementia, and non-Alzheimer’s-non-vascular dementia). We also examined the relationship between various risk factors and risk of all-cause dementia in type 1 diabetes. Results After a median follow-up time of 14.3 [7.9-20.0] years, dementia was recorded in 530 (1.2%) individuals with type 1 diabetes and 1,867 (0.9%) age-, sex- and county-matched controls (mean baseline age 33.0 (14.0) years). Compared to controls, individuals with type 1 diabetes had a higher risk of all-cause dementia (HR 2.02 [95%CI:1.83-2.23], Alzheimer’s disease (HR 1.38 [1.13-1.69]), vascular dementia (HR 3.73 [95%CI:3.07-4.52]) and non-Alzheimer’s-non-vascular dementia (HR 1.87 [95%CI:1.63-2.15]). Risk factors related to dementia risk in type 1 diabetes beyond age were lower education level, being single, higher systolic blood pressures, higher HbA1c, history of stroke/TIA, history of cardiovascular disease, and longer diabetes duration. Conclusions The risk of all-cause dementia and dementia subtypes is higher in individuals with type 1 diabetes compared to matched controls.