Mechanisms for racial and ethnic disparities in glycemic control in middle-aged and older Americans in the health and retirement study

Background: Mechanisms for racial/ethnic disparities in glycemic control are poorly understood. Methods: A nationally representative sample of 1901 respondents 55 years or older with diabetes mellitus completed a mailed survey in 2003; 1233 respondents completed valid at-home hemoglobin A(1c) (HbA(1c)) kits. We constructed multivariate regression models with survey weights to examine racial/ethnic differences in HbA(1c) control and to explore the association of HbA(1c) level with sociodemographic and clinical factors, access to and quality of diabetes health care, and self-management behaviors and attitudes. Results: There were no significant racial/ethnic differences in HbA(1c) levels in respondents not taking antihy-perglycemic medications. In 1034 respondents taking medications, the mean HbA(1c) value (expressed as percentage of total hemoglobin) was 8.07% in black respondents and 8.14% in Latino respondents compared with 7.22% in white respondents (P < . 001). Black respondents had worse medication adherence than white respondents, and Latino respondents had more diabetes-specific emotional distress (P < . 001). Adjusting for hypothesized mechanisms accounted for 14.0% of the higher HbA(1c) levels in black respondents and 19.0% in Latinos, with the full model explaining 22.0% of the variance. Besides black and Latino ethnicity, only insulin use (P < . 001), age younger than 65 years (P = . 007), longer diabetes duration (P = . 004), and lower self-reported medication adherence (P = . 04) were independently associated with higher HbA(1c) levels. Conclusions: Latino and African American respondents had worse glycemic control than white respondents. Socioeconomic, clinical, health care, and self-management measures explained approximately a fifth of the HbA(1c) differences. One potentially modifiable factor for which there were racial disparities-medication adherence-was among the most significant independent predictors of glycemic control.