Ethnic, Racial, and Educational Differences in CVD and Diabetes Control — Can Insurance Coverage Mitigate Disparities?

Abstract & Commentary

By Susan T. Marcolina, MD, FACP. Dr. Marcolina is a board-certified internist and geriatrician in Issaquah, WA; she reports no financial relationship to this field of study.

Synopsis: Subgroups of U.S. adults who are minorities, poor, or undereducated with chronic cardiovascular risk factors such as hypertension, diabetes, and hypercholesterolemia have large disparities in treatment for these conditions compared with white, high school-educated adults when they are uninsured or underinsured. Such disparities adversely impact risk of significant morbidity and mortality from cardiovascular disease (CVD). Insurance coverage with Medicare after age 65, however, mitigates many disparities by virtue of expansion of access to medical and laboratory evaluation and therefore to subsequent dietary, pharmacologic, and diagnostic management strategies that optimize control of blood pressure as well as serum levels of glucose and cholesterol.

Source: McWilliams JM, et al. Differences in control of cardiovascular disease and diabetes by race, ethnicity, and education: U.S. trends from 1999 to 2006 and effects of Medicare coverage. Ann Intern Med 2009;150:505-515.

Mcwilliams et al examined data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2006 on a cross-section of more than 12,000 U.S. adults ages 40-85 years who either had diabetes, hypertension, coronary heart disease (CHD), or stroke, or had physical exam findings or laboratory results that indicated the presence of these conditions. Disease control for each of these conditions was defined, according to standard recommendations, as hemoglobin A1C levels less than 7% among participants with diabetes,1 average blood pressure less than 140/90 mmHg for those with hypertension, (though the Seventh Joint National Committee [JNC 7] on Prevention, Detection, Evaluation and Therapy of High Blood Pressure would consider individuals with systolic blood pressures of 120-139 mmHg or diastolic blood pressures of 80-89 mmHg as prehypertensive and in need of lifestyle modifications of sodium restriction, weight loss, and exercise to prevent CVD),2 and total cholesterol levels less than 200 mg/dL for patients with diabetes, heart disease, or stroke.3 Over the eight years of this study, these authors showed that despite age- and sex-adjusted improvement in the control of blood pressure, hemoglobin A1C, and cholesterol levels, significant disparities existed for certain patient subgroups.

Black and Hispanic adults had significantly lower rates of blood pressure control (only 44% achieving BP goal, P < 0.001; and 42.5% achieving BP goal, P < 0.001, respectively), compared to white adults (52.8% at BP goal) with hypertension. Similarly, for adults with diabetes, levels of hemoglobin A1C were significantly higher with lower rates of glycemic control in black (only 41.6% reaching goal AIC level, P < 0.001) and Hispanic (only 37.8% reaching goal hemoglobin A1C level, P < 0.001) adults compared to white adults (58.1% achieving hemoglobin A1C goal). Mean systolic blood pressure and hemoglobin A1C levels were also significantly higher for less educated adults compared to more educated adults (140.8 vs. 138.4 mmHg, P = 0.034; and 7.6 % vs. 7.1%, respectively, P < 0.001). Thus, improved health care quality did not penetrate equally to different segments of the society.

Interestingly, however, McWilliams et al found that many health care disparities diminished significantly, though not completely, among participants 65 years of age or older, with Medicare insurance coverage. Whereas mean differences in systolic blood pressure between black and white study participants before age 65 was 7.0 mmHg, after age 65 and the access to care which Medicare brings to the minority, poor, and undereducated populace, this difference decreased to 2.8 mmHg. Control of diabetes was affected in the same way. Prior to age 65, the difference in mean hemoglobin A1C levels between whites and non-whites (black and Hispanic participants) was 0.9, whereas after age 65, this decreased to 0.2 (P < 0.001). The difference in mean hemoglobin A1C levels between non-high school graduates and graduates was 0.6% before age 65 and decreased to 0.1% after age 65 (P = 0.033). Furthermore, the group differences were greatest when comparisons of disease control measures were made before and after ages 65, 66, and 67, which strongly suggests the importance of Medicare acquisition to improved chronic cardiovascular disease control.


Given that coronary heart disease is the leading cause of death for both men and women in the United States4 and that several risk factors including hypertension, diabetes, and elevated serum cholesterol levels can be modified through diagnostic evaluation and dietary, lifestyle, and pharmacologic interventions to reduce mortality, morbidity, and, ultimately, cost of care, it is important to disseminate these disease-modifying interventions to all affected patients. It has been clear, however, that not all patients affected by chronic diseases have access to these same interventions that could improve their overall health, particularly when they lack insurance coverage.5 Since black, Hispanic, and less educated adults are generally more likely to be underinsured or uninsured, expansion of insurance coverage for these subgroups of patients may be of great benefit since it is known that patients without insurance delay seeking care due to concerns regarding expense, have more difficulty obtaining prescription medications, and receive less outpatient care and diagnostic testing.6,7 Certainly, Medicare acquisition after age 65 has been associated with decreased racial and socioeconomic differences in ability to obtain mammography and self-reported overall general health.8,9

When Taiwan implemented a universal national health insurance in 1995, life expectancy improved in the lower-ranked health class groups that had higher mortality rates before introduction of national health insurance, particularly with regard to cardiovascular diseases. Prior to institution of national health insurance, CVD mortality caused the greatest disparity between the health class groupings. According to Wen et al, utilization of medical services by the lower-ranked health classes increased and disparity narrowed compared to the highest-ranked health group; however, cost remained at approximately 5-6% of the gross domestic product.10 This is in contrast to the situation in the United States wherein health care expenditures account for 16% of GDP despite the fact that 50 million U.S. residents are uninsured and health care disparities are prevalent, particularly among the poor, minorities, and undereducated citizenry.11

McWilliams et al have provided data from a representative American population, which demonstrate that access to Medicare, the universal public insurance for U.S adults older than age 65, improves control of blood pressure, glucose, and cholesterol levels, important modifiable risk factors for cardiovascular disease, the leading cause of death in the United States. In this reviewer's opinion, and as supported by data like those presented here, it is time to improve quality of care and lessen health care expenditures by expanding access to include all U.S. residents. The provision of a national health insurance plan to United States residents would be a cost-effective, long-term investment strategy since persons with diabetes, hypertension, and heart disease and those with risk factors for these chronic diseases experience the majority of the preventable morbidity and mortality among uninsured older adults.12


1. Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). UK Prospective Diabetes Study (UKPDS) Group. Lancet 1998;352:837-853.

2. Chobanian AV, et al; National High Blood Pressure Education Program Coordinating Committee. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 report. U.S. Dept of Health and Human Services. National Institutes of Health; National Heart Lung and Blood Institute. Available at: Accessed June 6, 2009.

3. Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. Executive Summary of the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). JAMA 2001;285:2486-2497.

4. Centers for Disease Control and Prevention. FastStats: Leading Causes of Death. Available at: Accessed June 1, 2009.

5. Ayanian JZ, et al. Unmet health needs of uninsured adults in the United States. JAMA 2000;284:2061-2069.

6. Hadley J. Insurance coverage, medical care use, and short-term health changes following an unintended injury or the onset of a chronic condition. JAMA 2007;297:1073-1084.

7. Institute of Medicine. Insuring America's Health; Principles and Recommendations. Washington, DC: National Academies Press; 2004.

8. Card D, et al. The Impact of Nearly Universal Insurance Coverage on Health Care Utilization and Health: Evidence from Medicare. NBER Working Paper 10365. Cambridge, MA: National Bureau of Economic Research; 2004

9. Decker SL. Medicare and the health of women with breast cancer. J Hum Resour 2005;4:948-968.

10. Wen CP, et al. A 10-year experience with universal health insurance in Taiwan: Measuring changes in health and health disparity. Ann Intern Med 2008; 148:258-267.

11. Centers for Medicare and Medicaid Services. National Health Expenditures, 2007 Highlights. Available at: Accessed June 2, 2009.

12. McWilliams JM, et al. Health insurance coverage and mortality among the near-elderly. Health Aff (Millwood) 2004;23:223-233.