Disparities in HbA1c Levels Between African-American and Non-Hispanic White
Disparities in HbA1c Levels Between African-American and Non-Hispanic White
Objective: Among individuals with diabetes, a comparison of HbA1c (A1C) levels between African Americans and non-Hispanic whites was evaluated. Data sources included PubMed, Web of Science, the Cumulative Index to Nursing and Allied Health, the Cochrane Library, the Combined Health Information Database, and the Education Resources Information Center.
Research Design And Methods: We executed a search for articles published between 1993 and 2005. Data on sample size, age, sex, A1C, geographical location, and study design were extracted. Cross-sectional data and baseline data from clinical trials and cohort studies for African Americans and non-Hispanic whites with diabetes were included. Diabetic subjects aged <18 years and those with pre-diabetes or gestational diabetes were excluded. We conducted a meta-analysis to estimate the difference in the mean values of A1C for African Americans and non-Hispanic whites.
Results: A total of 391 studies were reviewed, of which 78 contained A1C data. Eleven had data on A1C for African Americans and non-Hispanic whites and met selection criteria. A meta-analysis revealed the standard effect to be 0.31 (95% CI 0.39-0.25). This standard effect correlates to an A1C difference between groups of ∼0.65%, indicating a higher A1C across studies for African Americans. Grouping studies by study type (cross-sectional or cohort), method of data collection for A1C (chart review or blood draw), and insurance status (managed care or nonmanaged care) showed similar results.
Conclusions: The higher A1C observed in this meta-analysis among African Americans compared with non-Hispanic whites may contribute to disparity in diabetes morbidity and mortality in this population.
Ethnic minorities in the U.S. are disproportionately affected by most diabetes-related complications, including diabetic retinopathy, lower-extremity amputation, and end-stage renal disease. Although diabetes has a major adverse impact on life-years and quality-adjusted life-years in all U.S. subpopulations, the impact is even greater among minority individuals, including African Americans and Hispanics. Specifically, many diabetes complications are experienced at a higher rate in African Americans than in non-Hispanic whites. For example, the prevalence and severity of diabetic retinopathy is 46% higher in African Americans than in non-Hispanic whites, and African Americans with diabetes are more likely to develop kidney disease and kidney failure requiring dialysis than non-Hispanic whites. Although racial disparities in complications are somewhat less marked in populations receiving uniform access to care, disparities in HbA1c (A1C) level among African Americans, Asians, and Latinos have been shown compared with non-Hispanic whites. Improvements in glycemic control have been shown to prevent microvascular complications, and large trials have demonstrated the need for glucose control among patients with diabetes. Literature has suggested that A1C control may be poorer among minority populations than among nonminority populations. A number of factors may drive differences in A1C control: biological, socioeconomic, and quality-of-care factors have been suggested. Lack of access to health care may also affect diabetes care among minority individuals. African Americans report lower rates of health insurance than non-Hispanic whites. This barrier to care can lead to delayed diagnosis and increased years of exposure to untreated diabetes. Other studies have found that African Americans are less likely to have prescription drug coverage, which limits their ability to afford medications once they have been diagnosed. Differences in the frequency of obtaining common preventive care measures related to diabetes also have been implicated in the quality-of-care disparity between African Americans and non-Hispanic whites. Of special concern is the suggestion that minority populations receive less optimal diabetes care even after they access the health care system.
A recent review of studies reported overall poorer glycemic control in U.S. adults with diabetes as measured by A1C. The consistency of a higher A1C across comparative studies of African Americans and non-Hispanic whites with diabetes has not been examined. To get a better representation of whether differences in A1C levels exist between African Americans and non-Hispanic whites with diabetes, we reviewed the literature (1993-2005) for which comparisons between populations were made and conducted a meta-analysis using standardized statistical methods. This time period was selected because the A1C measurement has become more standardized over the past 10 years.
Abstract and Introduction
Abstract
Objective: Among individuals with diabetes, a comparison of HbA1c (A1C) levels between African Americans and non-Hispanic whites was evaluated. Data sources included PubMed, Web of Science, the Cumulative Index to Nursing and Allied Health, the Cochrane Library, the Combined Health Information Database, and the Education Resources Information Center.
Research Design And Methods: We executed a search for articles published between 1993 and 2005. Data on sample size, age, sex, A1C, geographical location, and study design were extracted. Cross-sectional data and baseline data from clinical trials and cohort studies for African Americans and non-Hispanic whites with diabetes were included. Diabetic subjects aged <18 years and those with pre-diabetes or gestational diabetes were excluded. We conducted a meta-analysis to estimate the difference in the mean values of A1C for African Americans and non-Hispanic whites.
Results: A total of 391 studies were reviewed, of which 78 contained A1C data. Eleven had data on A1C for African Americans and non-Hispanic whites and met selection criteria. A meta-analysis revealed the standard effect to be 0.31 (95% CI 0.39-0.25). This standard effect correlates to an A1C difference between groups of ∼0.65%, indicating a higher A1C across studies for African Americans. Grouping studies by study type (cross-sectional or cohort), method of data collection for A1C (chart review or blood draw), and insurance status (managed care or nonmanaged care) showed similar results.
Conclusions: The higher A1C observed in this meta-analysis among African Americans compared with non-Hispanic whites may contribute to disparity in diabetes morbidity and mortality in this population.
Introduction
Ethnic minorities in the U.S. are disproportionately affected by most diabetes-related complications, including diabetic retinopathy, lower-extremity amputation, and end-stage renal disease. Although diabetes has a major adverse impact on life-years and quality-adjusted life-years in all U.S. subpopulations, the impact is even greater among minority individuals, including African Americans and Hispanics. Specifically, many diabetes complications are experienced at a higher rate in African Americans than in non-Hispanic whites. For example, the prevalence and severity of diabetic retinopathy is 46% higher in African Americans than in non-Hispanic whites, and African Americans with diabetes are more likely to develop kidney disease and kidney failure requiring dialysis than non-Hispanic whites. Although racial disparities in complications are somewhat less marked in populations receiving uniform access to care, disparities in HbA1c (A1C) level among African Americans, Asians, and Latinos have been shown compared with non-Hispanic whites. Improvements in glycemic control have been shown to prevent microvascular complications, and large trials have demonstrated the need for glucose control among patients with diabetes. Literature has suggested that A1C control may be poorer among minority populations than among nonminority populations. A number of factors may drive differences in A1C control: biological, socioeconomic, and quality-of-care factors have been suggested. Lack of access to health care may also affect diabetes care among minority individuals. African Americans report lower rates of health insurance than non-Hispanic whites. This barrier to care can lead to delayed diagnosis and increased years of exposure to untreated diabetes. Other studies have found that African Americans are less likely to have prescription drug coverage, which limits their ability to afford medications once they have been diagnosed. Differences in the frequency of obtaining common preventive care measures related to diabetes also have been implicated in the quality-of-care disparity between African Americans and non-Hispanic whites. Of special concern is the suggestion that minority populations receive less optimal diabetes care even after they access the health care system.
A recent review of studies reported overall poorer glycemic control in U.S. adults with diabetes as measured by A1C. The consistency of a higher A1C across comparative studies of African Americans and non-Hispanic whites with diabetes has not been examined. To get a better representation of whether differences in A1C levels exist between African Americans and non-Hispanic whites with diabetes, we reviewed the literature (1993-2005) for which comparisons between populations were made and conducted a meta-analysis using standardized statistical methods. This time period was selected because the A1C measurement has become more standardized over the past 10 years.
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