Racial/ethnic differences in dementia risk among older type 2 diabetes patients: The Diabetes and Aging Study
- Elizabeth R. Mayeda, PhD, MPH1,
- Andrew J. Karter, PhD2,
- Elbert S. Huang, MD, MPH3,
- Howard H. Moffet, MPH2,
- Mary N. Haan, DrPH, MPH1 and
- Rachel A. Whitmer, PhD2⇑
- 1Department of Epidemiology and Biostatistics, University of California, San Francisco
- 2Division of Research, Kaiser Permanente Northern California
- 3Section of General Internal Medicine, University of Chicago
- Corresponding Author: Rachel A. Whitmer, Email:
Background: Although those with type 2 diabetes have double the risk of dementia, potential racial/ethnic differences in dementia risk have not been explored in this population. We evaluated racial/ethnic differences in dementia and potential explanatory factors among older diabetes patients.
Methods: We identified 22,171 diabetes patients without preexisting dementia, aged ≥60 years (14,546 non-Hispanic whites, 2,484 African Americans, 2,363 Latinos, 2,262 Asians, 516 Native Americans) from the Kaiser Permanente Northern California Diabetes Registry. We abstracted prevalent medical history (1/1/1996-12/31/1997) and dementia incidence (1/1/1998-12/31/2007) from medical records and calculated age-adjusted incidence densities. We fit Cox proportional hazards models adjusted for age, sex, education, diabetes duration, and markers of clinical control.
Results: Dementia was diagnosed in 3,796 (17.1%) patients. Age-adjusted dementia incidence densities were highest among Native Americans (34/1,000 person-years) and African Americans (27/1,000 person-years) and lowest among Asians (19/1,000 person-years). In the fully-adjusted model, hazard ratios (95% CIs) (relative to Asians) were 1.64 (1.30-2.06) for Native Americans, 1.44 (1.24-1.67) for African Americans, 1.30 (1.15-1.47) for non-Hispanic whites, and 1.19 (1.02-1.40) for Latinos. Adjustment for diabetes-related complications and neighborhood deprivation index did not change results.
Conclusions: Among type 2 diabetes patients followed for ten years, African Americans and Native Americans had a 40-60% greater risk of dementia compared to Asians, and risk was intermediate for non-Hispanic whites and Latinos. Adjustment for sociodemographics, diabetes-related complications, and markers of clinical control did not explain observed differences. Future studies should investigate why these differences exist and ways to reduce them.
- Received January 25, 2013.
- Accepted November 17, 2013.
- © 2013 by the American Diabetes Association.
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