Early-Onset Dementia Risk Escalates with Diabetes Duration: Insights from a Nationwide Cohort Study

The prevalence of diabetes mellitus and early-onset dementia (EOD), defined as dementia diagnosed at an age <65 years, is increasing worldwide, with significant socioeconomic implications. We investigated the association between diabetes, prediabetes, and EOD, focusing on the influence of diabetes duration on EOD risk.

Using the Korean National Health Insurance Service database, we analyzed data from 1,979,509 patients aged 40-60 years who underwent health checkups in 2009. Patients were categorized into five groups: normal, impaired fasting glucose (IFG), newly diagnosed diabetes, diabetes duration <5 years, and diabetes duration ≥5 years. Cox proportional hazard models were used to estimate the adjusted hazard ratios (aHRs) for EOD after adjusting for demographic and clinical covariates.

During the observation period (mean 7.75 years), 8,921 patients with EOD were identified. The diabetes group demonstrated a significantly higher incidence of EOD compared to the normal group (aHR, 1.334; 95% confidence interval [CI], 1.226 to 1.451). EOD risk increased with longer diabetes duration, with the highest risk observed in patients with diabetes ≥5 years (aHR, 1.543; 95% CI, 1.368 to 1.741). No significant difference was observed between the IFG and normal groups (aHR, 0.989; 95% CI, 0.938 to 1.043). Additionally, the hypertension group exhibited a significantly higher incidence of EOD compared to the non-hypertension group (aHR, 1.364; 95% CI, 1.291 to 1.442).

Diabetes is independently associated with increased risk of EOD, and this risk increases with longer diabetes duration. This association remained significant regardless of the presence and duration of hypertension.