Risk factors for dementia in patients over 65 with diabetes

Objective: This study identified factors in patients with diabetes associated with risk of developing dementia.

Research design and methods: This retrospective, longitudinal study used a national cohort of US Veterans with diabetes 65 years or older to examine incidence of dementia over 2 years. A multivariable Cox regression model was used to estimate risk of developing dementia associated with sociodemographic factors, use of diabetes medications, and duration of diabetes.

Results: In all, 377,838 patients (average age, 75.53 ± 6.07 years) were studied. Over the 2 year follow-up, 14,580 (3.85%) were diagnosed with dementia. Major risk factors for dementia were age >75 years (75-85 years, hazard ratio [HR] 2.092, 95% confidence interval [CI] 2.017-2.169; ≥85 years, HR 3.468, CI 3.274-3.672), race black versus white, HR 1.218, CI 1.164-1.274), Southern residence (HR = 1.181, CI 1.133-1.232), and diabetes duration (HR for 5 years or more, 1.428, CI 1.357-1.504). There was a reduced HR for dementia with use of an oral hypoglycemic agent (HR 0.940, CI 0.909-0.972) and HMG-CoA reductase inhibitors (HR, 0.875, CI 0.846-0.906). There was no change in HR with insulin use (HR 1.024, CI 0.983-1.067).

Conclusions: Several important factors were identified that are associated with increased dementia risk, and two factors were identified that are associated with reduced risk. It will be important to ascertain whether risk-factor modification reduces the HR for dementia in persons with diabetes, and to further examine effects of medication use for comorbid conditions.