Background/Aims: Diabetes mellitus (DM) is a recognized risk factor for dementia in stroke survivors. However, the relationship between DM duration and the risk of developing dementia in this population remains unclear. Therefore, our research aims to clarify the relationship between the duration of DM and the risk of developing all-cause dementia, which includes Alzheimer's disease(AD) and vascular dementia(VaD), in patients with a history of stroke.
Methods: We conducted a retrospective cohort study using the Korean National Health Insurance Database, analyzing 118,790 individuals with a history of stroke but no previous dementia diagnosis, from 2009 to 2018. We categorized diabetic status into five groups: normoglycemia, impaired fasting glucose, newly diagnosed DM, and established DM with durations of less than 5 years and 5 years or more.
Results and Conclusion: Over an average follow-up period of 7.3 years, 16.7% of 118,790 participants developed dementia. We found that individuals with a history of DM for over five years had a significantly higher risk of developing all-cause dementia (aHR 1.466, 1.408-1.527). In particular, the risks of developing AD and VaD were increased by 43.4% and 51.4%, respectively, for individuals with a DM duration exceeding five years (aHR 1.434, [1.366-1.505] for AD and aHR 1.514 [1.365-1.679] for VaD). Subgroup analysis revealed that those under the age of 65 with an extended duration of DM faced a significantly increased risk of dementia. Our findings emphasize the importance of proactive dementia prevention approaches in stroke survivors, particularly those with long-standing DM.