Type 2 diabetes and ethnic disparities in cognitive impairment.

OBJECTIVES

We explored whether ethnic differences in type 2 diabetes (T2D) explain ethnic disparities in cognitive impairment.

DESIGN

Longitudinal study.

SETTING

A cohort study of multiethnic community-dwelling elderly persons in Northern Manhattan, New York.

PARTICIPANTS

941 participants aged > or =65 years without prevalent cognitive impairment or dementia (CID) were followed for a median of 7.1 years.

MAIN OUTCOMES MEASURES

CID was defined by a clinical dementia rating > or = .5. CID risk attributable to T2D was estimated for each ethnic group using the hazard ratio (HR) relating T2D and CID and the ethnic prevalence of T2D.

RESULTS

448 participants developed CID; 69 (31.4%) non-Hispanic whites (whites); 152 (48.6%) non-Hispanic-blacks (blacks); 227 (55.6%) Hispanics, P < .001. T2D prevalence was 8.2% in Whites, 20.1% in blacks, and 19.6% in Hispanics, P < .001. Controlling for age, sex, education, and APOE E4, the HR relating T2D and CID was 1.63 (95% CI 1.26, 2.09). CID attributable to T2D was higher in blacks and Hispanics compared to Whites (11.4% vs. 4.9%; P = .06). We estimated that reducing the ethnic disparities in diabetes prevalence could reduce the CID ethnic disparities by 17%.

CONCLUSIONS

Reducing ethnic differences in T2D prevalence could partially reduce ethnic differences in incident CID.