Racial/ethnic differences in dementia risk among older type 2 diabetes patients: The Diabetes and Aging Study

  1. Rachel A. Whitmer, PhD2
  1. 1Department of Epidemiology and Biostatistics, University of California, San Francisco
  2. 2Division of Research, Kaiser Permanente Northern California
  3. 3Section of General Internal Medicine, University of Chicago
  1. Corresponding Author: Rachel A. Whitmer, Email: rachel.whitmer{at}kp.org

Abstract

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.

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  1. Diabetes Care
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