The use of metformin in older patients with type 2 diabetes is associated with a lower risk for dementia compared with the use of a sulfonylurea, according to the results of a retrospective cohort study published in Neurology.
A cohort of US veterans age ≥65 with type 2 diabetes, who were new users of either metformin or a sulfonylurea and did not have dementia, were enrolled in the study. Follow-up took place after 2 years of treatment. In order to account for confounding by indication, the investigators developed a propensity score (PS) and utilized inverse probability of treatment weighting (IPTW) methods. The hazard ratio (HR) of incident dementia was estimated via Cox proportional models.
The researchers identified 17,200 new users of metformin and 11,440 new users of a sulfonylurea (mean age, 73.5; mean HbA1c, 6.8%). A total of 4906 cases of dementia were diagnosed over 5-year follow-up period, with 2177 (12.7%) in metformin users and 2729 (23.9%) in sulfonylurea users. The crude HR for any dementia diagnosed in metformin vs sulfonylurea users was 0.67 (95% CI, 0.61-0.73; P <.001) and 0.78 (95% CI, 0.72-0.83; P <.001) in patients age <75 and ≥75, respectively.
After adjustment, the results continued to be statistically significant in veterans age <75 (HR 0.89; 95% CI, 0.79-0.99; P =.033) but not in veterans ≥75 (HR 0.96; 95% CI, 0.87-1.05; P =.332). A significantly lower risk for developing dementia was also observed in a subset of younger, white veterans with hemoglobin A1c (HbA1c) levels ≥7% (HR 0.76; 95% CI, 0.63-0.91; P =.003) and with normal renal function (HR, 0.86; 95% CI, 0.76-0.97; P =.019).
The findings of this study demonstrate that metformin is linked to a lower risk for dementia compared with sulfonylureas in veterans age <75 with type 2 diabetes. Additional research is warranted in order to identify which patients might benefit from metformin therapy for the prevention of dementia.
Orkaby AR, Cho K, Cormack J, Gagnon DR, Driver JA. Metformin vs sulfonylurea use and risk of dementia in US veterans aged ≥65 years with diabetes [published online September 27, 2017]. Neurology. doi:10.1212/WNL.0000000000004586