Type 2 diabetes and later cognitive function in older American Indians: The Strong Heart Study

Objectives Insulin resistance is a substantial health issue for American Indians, with type 2 diabetes overrepresented in this population as compared with non-Hispanic whites. Insulin resistance and its related conditions in turn increase risk for dementia and cognitive impairment. The aim of the current study was to determine whether type 2 diabetes and insulin resistance at midlife was associated with later-life cognitive testing in a large sample of older American Indians, aged 65 and older. Methods American Indian participants who underwent both fasting blood draw as part of the Strong Heart Study and had subsequent cognitive testing as part of the later adjunct Cerebrovascular Disease and its Consequences in American Indians study were included (n = 790). Regression models examined type 2 diabetes and impaired fasting glucose and subsequent cognitive test performance as part of a longitudinal study design. The relationship between a continuous measure of insulin resistance and later cognitive test performance was assessed using generalized estimating equations. Results Controlling for demographic and clinical factors, verbal fluency and processing speed/working memory were significantly negatively associated with having type 2 diabetes and with insulin resistance, but not with impaired fasting glucose. Conclusion In this sample of American Indians, type 2 diabetes at midlife was associated with subsequent lower performance on measures of executive function. These results may have important implications for future implementation of diagnostic and intervention services in this population.