Association between comorbidities and dementia in diabetes mellitus patients: population-based retrospective cohort study

Aims: Most diabetes mellitus (DM) patients have several comorbidities; the correlation of these comorbidities with dementia in DM requires clarification. Methods: Using claims data from Taiwan National Health Insurance, we identified 33,709 DM adults before the year 2000 and randomly selected 67,066 non-DM patients matched by sex and age. Subjects were followed until diagnosis with dementia, excluded due to death/withdrawal from the insurance program, or followed until 2011. We compared the incidence and hazard ratio (HR) for dementia in both cohorts. Results: Comorbidities were more prevalent in DM patients, including hypertension, hyperlipidemia, stroke, coronary artery and/or kidney disease. The HR was higher for the DM cohort with comorbidities than those without: 1.88 vs. 1.46 with hypertension; 1.56 vs. 1.39 with hyperlipidemia; 1.73 vs. 1.37 with coronary artery disease; 2.36 vs. 2.29 with stroke and 1.88 vs. 1.50 with kidney disease. The HR for dementia in diabetics rose from 1.41 in those without comorbidities to 2.49 in those with >= 4 comorbidities. In the DM cohort, HR was 1.22 for non-insulin-users and 1.41 for insulin-users, and 1.49 for type 1 DM and 1.23 for type 2 DM. Conclusion: Diabetic patients have an elevated risk of dementia, and comorbidity increases this risk. (C) 2015 Elsevier Inc. All rights reserved.