Dementia Risk in Type 2 Diabetes Patients: Acarbose Use and Its Joint Effects with Metformin and Pioglitazone

This population-based retrospective cohort study investigated dementia risk associated with acarbose in patients with type 2 diabetes mellitus by using Taiwan's National Health Insurance database. A cohort of 15,524 matched pairs of ever and never users of acarbose based on propensity score matching was enrolled from new-onset type 2 diabetes patients from 1999 to 2006. Patients who were alive on January 1, 2007, were followed up for dementia until December 31, 2011. Adjusted hazard ratios were estimated using Cox proportional hazards models. The results revealed that the incident case numbers (incidence rates) of dementia were 264 (407.19 per 100,000 person-years) for never users and 231 (337.94 per 100,000 person-years) for ever users. The hazard ratio for ever users versus never users was 0.841 (95% confidence interval, 0.704-1.005) and 0.918 (0.845-0.998) for every 1-year increment of cumulative duration of acarbose therapy. Subgroup analyses showed that the reduced risk associated with acarbose was only observed in women (adjusted hazard ratio, 0.783; 95% confidence interval, 0.618-0.992) and in non-users of metformin (adjusted hazard ratio, 0.635; 95% confidence interval, 0.481-0.837). A model comparing different combinations of acarbose, metformin, and pioglitazone suggested that users of all three drugs had the lowest risk of dementia (hazard ratio, 0.406; 95% confidence interval, 0.178-0.925). In conclusion, reduced risk of dementia associated with acarbose is observed in the female sex and in non-users of metformin. Moreover, users of all three drugs (acarbose, metformin, and pioglitazone) have the lowest risk of dementia.