Type 2 diabetes and antidiabetic medications in relation to dementia diagnosis

Background: Type 2 diabetes (T2D) has been shown to increase dementia risk, but few studies evaluated the relationship between antidiabetic treatment and dementia. Methods: We followed up 67,731 participants who were nondemented, nondiabetic, aged 65 or over at baseline from January 2004 to December 2009, to observe the onset of T2D (median follow-up 2.4 years), and to compare the risk of the development of dementia associated with particular types of antidiabetic medication among participants with T2D who had solely one type of antidiabetic agents throughout the follow-up period (median follow-up for participants with T2D 3.1 years). Results: The hazard ratio for dementia diagnosis in the new-onset T2D participants compared with the non-T2D participants was 1.56 (95%CI: 1.39-2.18). The relative rate of dementia was 5.31 (95% CI: 1.89-14.96) for participants taking thiazolidinediones (n = 28) and 1.22 (95% CI: 0.78-1.91) for those taking sulfonylureas (n = 796) compared to those taking metformin (n = 1,033). The risk of dementia was higher in ever (n = 841) versus never users (n = 4,579) of thiazolidinediones: 1.44 (95% CI: 1.12-1.86). Conclusions: Diabetes is associated with an increased risk of dementia. The risk effect becomes weaker provided that participants take sulfonylureas or metformin rather than thiazolidinediones for a longer period.