Context: Diabetes is a risk factor for dementia, but the effects of diabetic severity on dementia are unclear.
Objective: The purpose of this study was to investigate the association between the severity and progress of diabetes and the risk of dementia.
Design and setting: We conducted a 12-year population-based cohort study of new-onset diabetic patients from the Taiwan National Health Insurance Research Database. The diabetic severity was evaluated by the adapted Diabetes Complications Severity Index (aDCSI) from the prediabetic period to the end of follow-up. Cox proportional hazard regressions were used to calculate the hazard ratios (HRs) of the scores and change in the aDCSI.
Participants: Participants were 431,178 new-onset diabetic patients who were older than 50 years and had to receive antidiabetic medications.
Main outcome: Dementia cases were identified by International Classification of Diseases, ninth revision, code (International Classification of Diseases, ninth revision, codes 290.0, 290.1, 290.2, 290.3, 290.4, 294.1, 331.0), and the date of the initial dementia diagnosis was used as the index date.
Results: The scores and change in the aDCSI were associated with the risk of dementia when adjusting for patient factors, comorbidity, antidiabetic drugs, and drug adherence. At the end of the follow-up, the risks for dementia were 1.04, 1.40, 1.54, and 1.70 (P < .001 for trend) in patients with an aDCSI score of 1, 2, 3, and greater than 3, respectively. Compared with the mildly progressive patients, the adjusted HRs increased as the aDCSI increased (2 y HRs: 1.30, 1.53, and 1.97; final HRs: 2.38, 6.95, and 24.0 with the change in the aDCSI score per year: 0.51-1.00, 1.01-2.00, and > 2.00 vs < 0.50 with P < .001 for trend).
Conclusions: The diabetic severity and progression reflected the risk of dementia, and the early change in the aDCSI could predict the risk of dementia in new-onset diabetic patients.