Type 1 Diabetes Linked to Increased Dementia Risk

Patients with type 1 diabetes (T1D) are at higher risk for all-cause and subtype-specific dementia than the general population. These findings, from a cohort study, were published in Diabetes Care.

Due to improvements in glucose-lowering therapies, the population of older adults with T1D is increasing, as the proportion of individuals with T1D aged 65 years and older increased by 180% from 1990 to 2019 worldwide.

To assess whether T1D is associated with increased risk for dementia with aging, investigators from the University Medical Center Utrecht in the Netherlands sourced data from the Swedish National Diabetes Register (NDR). Adults (n=43,440) with documented T1D between 1996 and 2019 were matched with adults (n=217,109) without diabetes and evaluated for dementia onset through 2020.

The T1D cohort, comprising 44% women, had a mean (SD) age of 33.0 (14.0) years, age at T1D diagnosis of 14.0 (7.6) years, and T1D duration of 18.1 (14.1) years.

[T]his study showed that individuals with type 1 diabetes have a twofold higher risk for all-cause dementia compared with matched controls.

During a median follow-up of 14.3 years, the rates of all-cause dementia were 1.2% and 0.9% among the T1D and control cohorts, respectively. Stratified by subtype, the T1D vs control cohort had higher rates of vascular dementia (0.37% vs 0.14%) and non-Alzheimer-nonvascular dementia (0.58% vs 0.45%) but comparable rates of Alzheimer disease (AD; 0.26% vs 0.27%).

Compared with the control cohort, T1D was associated with higher rates of all-cause dementia (standardized incidence ratio [sIR], 1.59; 95% CI, 1.46-1.73) as well as vascular dementia (sIR, 2.73; 95% CI, 2.32-3.18) and non-Alzheimer-nonvascular dementia (sIR, 1.49; 95% CI, 1.31-1.68). For AD, T1D tended to be associated with a higher rate (sIR, 1.15; 95% CI, 0.95-1.38).

After adjusting for age, gender, marital status, and education, T1D was associated with increased risks for:

• All-cause dementia (adjusted hazard ratio [aHR], 2.02; 95% CI, 1.83-2.23);
• Vascular dementia (aHR, 3.73; 95% CI, 3.07-4.52);
• Non-Alzheimer-nonvascular dementia (aHR, 1.87; 95% CI, 1.63-2.15); and,
• AD (aHR, 1.38; 95% CI, 1.13-1.69).

Among patients with T1D, all-cause dementia risk was associated with:

• History of stroke or transient ischemic attack (aHR, 2.65; 95% CI, 1.91-3.67; P <.001);
• Single marital status (aHR, 1.56; 95% CI, 1.23-1.97; P <.001);
• History of cardiovascular disease (aHR, 1.51; 95% CI, 1.20-1.91; P <.001);
• Age per 1-year increase (aHR, 1.14; 95% CI, 1.13-1.15; P <.001);
• Glycated hemoglobin (HbA_1c) per 10 mmol/mol increase (aHR, 1.10; 95% CI, 1.03-1.18; P =.01); and,
• Systolic blood pressure per 10 mmHg increase (aHR, 1.07; 95% CI, 1.02-1.13; P =.01)

On the other hand, all-cause dementia risk was inversely related with higher education attainment (aHR, 0.66; 95% CI, 0.55-0.79; P <.001) and BMI per 1 kg/m² increase (aHR, 0.97; 95% CI, 0.95-1.00; P =.04).

This study was limited by absence of data on potential dementia confounders, such as lifestyle factors or biomarker status.

The study authors concluded, “[T]his study showed that individuals with type 1 diabetes have a twofold higher risk for all-cause dementia compared with matched controls. The risk was the highest for the vascular dementia subtype.”

Disclosure: Multiple study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

This article originally appeared on Endocrinology Advisor