Type 2 Diabetes Disparities in Ethnic Minorities: Origin, Challenges, and Solutions
Posted November 04, 2009
It is estimated that more than 23 million Americans are diabetic, and the disease is disproportionately more common in ethnic minorities. Minorities also have higher rates of complications and comorbidities such as coronary artery disease or stroke. In addition, even when access to care is comparable, disparities persist in the quality of diabetes care that is provided to minority patients.
On September 15, 2009, the Academy convened experts in diabetes, metabolism, endocrinology, epidemiology, and cardiology to discuss disparities in the incidence and treatment of type 2 diabetes and associated comorbidities and complications. Enrique Caballero provided an overview of the biological, social, and cultural factors that influence the health disparities observed in diabetes, Harold Lebovitz, Guillermo Umpierrez, and Lawrence Young discussed the comorbidity of diabetes with cardiovascular disease, and Elizabeth Walker and Ann Albright discussed public health approaches to diabetes education and care.
Slides & Audio
Origins of Type 2 Diabetes Discrepancies
As Enrique Caballero of Harvard Medical School explains, understanding cultural differences and improving communication with minority populations will be an important part of addressing the diabetes epidemic.
Use the tabs above to find a meeting report and multimedia from this event.
Presentations are available from:
Enrique Caballero (Harvard Medical School)
Harold E. Lebovitz (State University of New York)
Guillermo E. Umpierrez (Emory University School of Medicine)
Lawrence H. Young (Yale University)
Elizabeth Walker (Albert Einstein College of Medicine)
Ann Albright (Centers for Disease Control and Prevention)
This program was supported by an educational grant from Takeda Pharmaceuticals North America, Inc.
This activity was supported by an educational grant from Lilly USA, LLC. For further information concerning Lilly grant funding visit the Lilly Grant Office.
This event was funded in part by the Life Technologies™ Foundation and by educational grants from Bayer HealthCare Diabetes Care and sanofi-aventis U.S.
Please see the Sponsorship tab above for a complete list of supporters.
- 00:011. Introduction; The role of race; Studies
- 07:302. Differences in insulin sensitivity and accumulation of abdominal fat; Unequal treatment
- 12:203. Causes of disparities in healthcare; Cultural influences on diabetes development
- 20:144. Language barriers; Communication problems
- 24:325. Health literacy; Culturally appropriate translation
- 27:256. Cross-cultural care; Summary and conclusio
CDC Diabetes Public Health Resource
The Centers for Disease Control and Prevention's diabetes information Web site for the public and health professionals.
The National Diabetes Education Program
A joint initiative of CDC and NIH, NDEP collaborates with over 200 partners to improve the treatment and outcomes for people with diabetes.
The New York City A1C Registry
As mandated by a 2006 amendment to the health code, laboratories are required to report the results of hemoglobin A1c blood tests to the NYC Department of Health and Mental Hygiene.
The National Institute of Diabetes and Digestive and Kidney Diseases, conducts and supports basic and clinical research.
Institute of Medicine. 2003. Unequal Treatment: Confronting Racial and Ethnic Disparities in Health Care. National Academies Press.
Caballero AE. 2005. Diabetes in minority populations. In: Kahn CR, Weir G, King G, et al., eds. Joslin's Diabetes Mellitus 14th ed. Lippincott, Williams & Wilkins.
Caballero AE, Bousquet-Santos K, Robles-Osorio L, et al. 2008. Overweight Latino children and adolescents have marked endothelial dysfunction and subclinical vascular inflammation in association with excess body fat and insulin resistance. Diabetes Care 31: 576-582. Full Text
Caballero AE. 2007. Type 2 diabetes in the Hispanic or Latino population: challenges and opportunities. Curr. Opin. Endocrinol. Diabetes Obes. 14: 151-157.
Caballero AE. 2007. Cultural competence in diabetes mellitus care: an urgent need. Insulin 2: 80–91. Full Text (PDF, 113 KB)
Hosler AS, Melnik TA. 2005. Population-based assessment of diabetes care and self-management among Puerto Rican adults in New York City. Diabetes Educ. 31: 418-426.
Banerji MA, Lebowitz J, Chaiken RL, et al. 1997. Relationship of visceral adipose tissue and glucose disposal is independent of sex in black NIDDM subjects. Am. J. Physiol. 273: E425-432.
Kirk JK, D'Agostino RB Jr, Bell RA, et al. 2006. Disparities in HbA1c levels between African-American and non-Hispanic white adults with diabetes: a meta-analysis. Diabetes Care 29: 2130-2136. Full Text
Kirk JK, Passmore LV, Bell RA, et al. 2008. Disparities in A1C levels between Hispanic and non-Hispanic white adults with diabetes: a meta-analysis. Diabetes Care 31: 240-246. Full Text
Skyler JS, Bergenstal R, Bonow RO, et al. 2009. Intensive glycemic control and the prevention of cardiovascular events: implications of the ACCORD, ADVANCE, and VA Diabetes Trials: a position statement of the American Diabetes Association and a Scientific Statement of the American College of Cardiology Foundation and the American Heart Association. Diabetes Care 32: 187-192. Full Text
Bax JJ, Young LH, Frye RL, et al. 2007. Screening for coronary artery disease in patients with diabetes. Diabetes Care 30: 2729-2736. Full Text
Wackers FJ, Young LH, Inzucchi SE, et al. 2004. Detection of silent myocardial ischemia in asymptomatic diabetic subjects: the DIAD study. Diabetes Care 27: 1954-1961. Full Text
Young LH, Wackers FJ, Chyun DA, et al. 2009. Cardiac outcomes after screening for asymptomatic coronary artery disease in patients with type 2 diabetes: the DIAD study: a randomized controlled trial. JAMA 301: 1547-1555. Full Text
Chamany S, Silver LD, Bassett MT,et al. 2009. Tracking diabetes: New York City's A1C Registry. Milbank Q. 87: 547-570.
Walker EA, Molitch M, Kramer MK, et al. 2006. Adherence to preventive medications: predictors and outcomes in the Diabetes Prevention Program. Diabetes Care 29: 1997-2002. Full Text
Walker EA, Schechter CB, Caban A, et al. 2008. Telephone intervention to promote diabetic retinopathy screening among the urban poor. Am. J. Prev. Med. 34: 185-191. Full Text
Saaddine JB, Cadwell B, Gregg EW, et al. 2006. Improvements in diabetes processes of care and intermediate outcomes: United States, 1988-2002. Ann. Intern. Med. 144: 465-474. Full Text (PDF, 134 KB)
Mary Ann Banerji, MD
SUNY Downstate Medical Center
e-mail | publications
Mary Ann Banerji is professor of medicine at SUNY Downstate Medical Center in Brooklyn. With an expertise in diabetes, she directs the Kings County Hospital Diabetes Clinic and SUNY Diabetes Treatment Center. She received her medical degree from Temple University School of Medicine in Philadelphia. She completed her residency in internal medicine and a fellowship in Endocrinology and Metabolism at SUNY Downstate Medical Center. Banerji's research interests are in type 2 diabetes among minorities, in particular African-American and South Asians. She described Flatbush Diabetes, an atypical form with features of both type 1 and type 2 diabetes among African Americans and is an expert in body composition. She pioneered the concept of long-term remission in type 2 diabetes induced by intensive treatment. In addition, she is actively involved in developing interventions to prevent diabetes and its complications at a community level. Banerji publishes and is actively involved in postgraduate and graduate medical education.
Ann Albright, PhD, RD
Centers for Disease Control and Prevention
e-mail | web site | publications
Ann Albright assumed the post of director, Division of Diabetes Translation (DDT) in January 2007. As director, Albright leads a team of more than 100 people who strive to eliminate the preventable burden of diabetes through leadership, research, programs, and policies that translate science into practice. Albright received her doctoral degree in exercise physiology from the Ohio State University. She completed a National Institutes of Health postdoctoral fellowship in nutrition at the University of California, Davis, and a clinical internship in nutrition at University of California, San Francisco (UCSF). Prior to commencing her post at the CDC, Albright served as chief of the California Diabetes Program for the California Department of Health Services, a position she held since 1995. Albright also held an academic appointment in the Institute for Health and Aging at UCSF. From 2003–2004, Albright served as the senior health policy advisor in the Office of the United States Surgeon General and led the Secretary of Health's Diabetes Detection Initiative.
Albright is well known for her work in diabetes including the implementation of evidence-based diabetes care guidelines, work on models of care in community clinics, and development of public awareness campaigns to increase the understanding of diabetes and importance of blood glucose, blood pressure, and lipid control. Albright is published in the areas of exercise, nutrition, body composition, diabetic nephropathy, the role of tissue glycosylation in diabetic complications, the feasibility of enhanced care among Medicaid recipients with type 2 diabetes, and public health practice in diabetes prevention and control. Albright has served in key leadership roles with the American Diabetes Association including her role as immediate-past president for health care and education, the American College of Sports Medicine, the American Association of Diabetes Educators, and the American Dietetic Association.
Enrique Caballero, MD
Harvard Medical School
e-mail | web site
Enrique Caballero is the director of the Latino Diabetes Initiative, director of medical affairs of professional education, staff endocrinologist, and clinical investigator at Joslin Diabetes Center. He is also assistant professor of medicine at Harvard Medical School. Caballero developed the Joslin Latino Diabetes Initiative that was launched in the summer of 2002 and that integrates culturally oriented activities in the areas of patient care and education, community outreach, research and professional education. His research interests include type 2 diabetes and cardiovascular disease prevention, endothelial dysfunction and diabetes in minority populations. He is a co-investigator of the National Diabetes Prevention Program, the LookAhead Program and the Diabetes Education Study, all sponsored by the National Institutes of Health. He is the principal investigator in studies assessing vascular abnormalities in obese Hispanic children, adolescents and young adults. He is also principal investigator in a study assessing biological, psychological, social and cultural factors influencing adherence to treatment in Latinos with diabetes.
Caballero graduated from the National University of Mexico Medical School where he was awarded with the "Gabino Barreda" medal for being the top student in his class. He then completed his residency in internal medicine and fellowship in endocrinology at the National Institute of Nutrition in Mexico, and went on to complete a master's degree in clinical epidemiology in Mexico. In addition, he completed a fellowship program in endocrinology and metabolism at the Lahey Clinic/Deaconess Hospital/Joslin Diabetes Center and the Program on Clinical Effectiveness at the Harvard School of Public Health. Caballero is the 2009 recipient of the Alberto Houssay award by the National Minority Quality Forum for his work on health care disparities.
Harold E. Lebovitz, MD
SUNY Health Sciences Center at Brooklyn
web site | publications
Harold Lebovitz is a professor of medicine in the Division of Endocrinology and Metabolism/Diabetes at the State University of New York, Health Sciences Center at Brooklyn. Lebovitz is an internationally recognized authority in the field of diabetes. He and his colleagues have contributed to the understanding of the pathogenesis of type 2 diabetes, particularly as it relates to ethic and racial differences, to mechanism of action and clinical utility of therapeutic agents used in the treatment of type 2 diabetes, and to the effects of body composition on insulin resistance and its associated abnormalities. He has published approximately 200 articles in peer-reviewed journals and 75 book chapters or books. Lebovitz has served on review committees for the American diabetes Association, the National Institutes of Health, and Veterans Administration and currently serves on several editorial boards. He has been the recipient of many awards, including the Albert E. Renold Medal of the American Diabetes Association in 1994, the Samuel Moses Oration Award of the Research Society for Study of Diabetes in India in 1993, and the Servier Medal of the Philippine Diabetes Association in 1999.
Guillermo E. Umpierrez, MD
Emory University School of Medicine
e-mail | publications
Guillermo Umpierrez is professor of medicine in the Division of Endocrinology, Metabolism, and Diabetes and associate director of the General Clinical Research Center at Emory University School of Medicine in Atlanta, Georgia. He is also director of the Diabetes Clinic and the Diabetes and Endocrinology Section of Grady Health Systems, also in Atlanta. Umpierrez received his medical degree in Ecuador and completed his internal medicine residency and endocrinology fellowship at Emory University School of Medicine. Umpierrez is the recipient of numerous teaching awards, including four Best Clinical Science Professor Awards, three Golden Apple Awards for Best Clinical Teacher, and the Silver Pear Award for Best Clinical Junior Faculty Mentor in the Department of Medicine at Emory University; the J. Willis Hurst Outstanding Bedside Teacher Award, from the Georgia ACP, and the AACE Outstanding Service Award for the Promotion of Endocrine Health of an Underserved Population.
He has published more than 100 scientific papers and book chapters, and has presented over 100 research abstracts at national and international scientific meetings. Umpierrez's current research interest includes mechanisms for β-cell dysfunction in African Americans; the effects of free fatty acids on insulin secretion, inflammation, and hypertension in obese patients; and management of hyperglycemia in critical and noncritical inpatients. His research program at Grady Hospital and Emory University is funded by the National Institutes of Health and the American Diabetes Association. Umpierrez also oversees funding of a bilingual diabetes education program for Latino patients in Georgia, and serves as the principal investigator for several multicenter research studies in the area of inpatient glycemic control.
Elizabeth A. Walker, PhD, RN
Albert Einstein College of Medicine
e-mail | web site | publications
Elizabeth Walker is a professor of medicine and professor of epidemiology & population health, and the director of the Prevention and Control Core for the Diabetes Research and Training Center (DRTC) at the Albert Einstein College of Medicine, Bronx, New York. Walker is principal investigator of a large, NIH-funded behavioral intervention study in minority diabetes populations, using telephonic interventions in Spanish and English to promote medication adherence, lifestyle change, and other self-management behaviors. Since its inception, she has also been a behavioral scientist and co-investigator for the multi-center Diabetes Prevention Program (DPP) and Outcomes Study and she co-chairs the DPP Medication Adherence Workgroup. Through the Prevention and Control Core of the DRTC she provides or facilitates various intervention and evaluation services to multiple health disparities projects in academic centers and in the community. Elizabeth is also a diabetes nurse specialist and has been a certified diabetes educator since 1986. In 2000 she served as National President, Health Care & Education, of the American Diabetes Association. In 2008 she was named a fellow of the American Association of Diabetes Educators (FAADE).
Lawrence H. Young, MD
e-mail | web site | publications
Lawrence Young is professor of medicine in the Section of Cardiology at Yale University School of Medicine. He is a board-certified clinical cardiologist and a fellow of the American Heart Association and American College of Cardiology. His interests center on cardiovascular disease in patients with insulin-resistance and diabetes and he has basic research interests on cardiac metabolism and the fundamental mechanisms by which cardiac cells adapt to stress and ischemia.
Young has been the recipient of numerous research grants, including support from the National Institutes of Health, American Heart Association, American Diabetes Association and Juvenile Diabetes Foundation. He is co-principal investigator of the DIAD (Detection of Ischemia in Asymptomatic Patients with Diabetes) Study, which is developing new approaches for identifying and treating heart disease in patients with diabetes. He is the cardiology principal investigator for the Insulin Resistance Intervention After Stroke Trial (IRIS), which is testing whether treating insulin resistance prevents stroke and myocardial infarction in non-diabetic patients. Young has held several leadership positions within the American Heart Association.
Theresa M. Wizemann
Theresa M. Wizemann is a science writer based in Doylestown, PA. Her writing focuses on biomedical science, health, and technology, including public policy, regulatory policy, biotechnology, and pharmaceutical research. Wizemann holds a PhD in microbiology and molecular genetics, awarded jointly from Rutgers University and the University of Medicine and Dentistry of New Jersey. She completed her postdoctoral research at the Rockefeller University in New York and is a former ASM/AAAS Congressional Science Fellow.
This program was supported by an educational grant from Takeda Pharmaceuticals North America, Inc.
This activity was supported by an educational grant from Lilly USA, LLC. For further information concerning Lilly grant funding visit the Lilly Grant Office.
This event was funded in part by the Life Technologies™ Foundation and by educational grants from Bayer HealthCare Diabetes Care and sanofi-aventis U.S.
- Epinex Diagnostics, Inc
- Ideal Protein
- SweetLeaf Sweetener®
- The Robert & Elizabeth Muller Foundation
How do you put together a program that is diverse enough to meet the needs of the many different subgroups of a particular ethnic group, such as Hispanics?
For the telephone intervention program, is a registered dietitian involved in the discussions of nutrition?
In surveys of medical records for statistical purposes, how far down in a hospital discharge record do you look to see if diabetes is a cofactor, considering it may not be among the primary or secondary coded entries?
Do patients understand what the A1c level is and what it means when it is reported to them?
What is the relative contribution of physical activity versus healthy eating?
Is there a role for the food industry, especially fast food companies, in addressing diabetes?
What is being done in schools with regard to food choices presented to children?
What options are available to those for whom measuring HbA1c is not possible (e.g. those with gestational diabetes or hemoglobinopathies, or dialysis patients)?
When recommending exercise to asymptomatic diabetic patients, should they have a stress test first?
How can we encourage healthcare practitioners and community members to become more involved in policy?
Enrique Caballero, Harvard Medical School
- Ethnic and racial minorities are increasing in number in the U.S., and there is a greater incidence of type 2 diabetes and associated complications in these groups.
- Even when access to care is comparable, disparities persist in the quality of care that is provided to minority patients.
- Cultural competence is an awareness and acceptance of cultural differences—and adaptation of skills accordingly—so that quality care can be administered to any patient, regardless of race, ethnicity, culture, class, or language proficiency.
Genetic and physiological differences in diabetes
The prevalence of type 2 diabetes varies among different ethnic groups in the United States. It is lowest in whites of European descent, and occurs at higher rates in African Americans, Hispanics, and Native Americans. In one extreme case, 70% of all Pima Indians above the age of 35 have type 2 diabetes. Meanwhile, the minority population in the U.S. reached 100.7 million in 2007 and continues to grow.
As Enrique Caballero of Harvard Medical School argued in an overview of the factors that influence disparities in the incidence of diabetes, such facts present a challenge to the way doctors and the health care system as a whole address the needs of these populations.
When considering the health of minority populations, Caballero pointed out, it is important to remember that race and ethnicity are not the same. Race is usually considered a biological concept, a collection of traits transmitted from generation to generation that allows classification of people into different groups. Ethnicity is primarily a social construct in which people identify themselves based on non-heritable characteristics such as culture, language, or religion. There are multiple subgroups within ethnicities. Americans who classify themselves as Hispanic or Latino, for example, may have ancestral roots in Mexico, Puerto Rico, Central and South America, Cuba, or elsewhere, and may be racially white, black, Indian, or something else.
Insulin sensitivity and fat deposition vary by race and ethnicity, and certain populations have a greater tendency to accumulate intra-abdominal/visceral fat. Genetic factors, such as insulin resistance, abdominal obesity, and beta cell dysfunction, are also known to predispose an individual to develop diabetes.
In one example, Caballero cited a study of non-diabetic Hispanic children that showed that overweight children had higher blood pressure and triglycerides, and were more insulin resistant, than lean children. Like their non-Hispanic counterparts, overweight Hispanic children expressed abnormal levels of plasma markers of endothelial dysfunction and inflammation (e.g., adhesion molecules, tumor necrosis factor alpha, white blood cell count) suggesting that there is a subclinical inflammatory process under way. This condition may predispose the children to developing type 2 diabetes and cardiovascular disease early in life. These data demonstrate the importance of implementing preventative strategies as early as possible.
Cultural and institutional factors
Caballero stressed, however, that social and cultural factors also influence the development of diabetes. Studies show that members of low socioeconomic groups are more likely to develop diabetes and complications. Access to healthcare is a key factor, as are daily life choices such as the willingness or ability to follow a meal plan, or to engage in physical activity.
A 2002 report from the Institute of Medicine concluded that even after controlling for access to care, racial and ethnic disparities in health outcomes persist. Disparities were consistently found across a wide range of healthcare settings, even when the analysis controlled for various confounders that could limit access to care (e.g., socioeconomic status or insurance coverage). To illustrate some of the differences in care, Caballero noted that higher hemoglobin A1c (HbA1c) levels, an indicator of diabetes risk, are generally observed in African American and Hispanic individuals compared to whites. However, a comparison of diabetes care for Puerto Rican adults in New York City with the city's general population showed that fewer minority patients received HbA1c or cholesterol tests, or were given blood pressure medication. Why is it, Caballero asked, that people in the same setting are not receiving the same quality of care?
In answering this question, three basic factors to consider are the patient, the provider, and the system. From the patient perspective, socioeconomic status, education and level of health literacy, personal health-seeking behavior, cultural factors, and mistrust all potentially impact the quality of care an individual ultimately receives. At the same time, providers may lack cultural awareness, subscribe to stereotypes or biases, lack resources, or face language barriers. The health care system overall also has a lack of culturally oriented programs and training, inadequate interpreter services, and operates under time pressures and resource constraints.
Improving communication is an important part of ensuring adequate healthcare to ethnic minorities.
Improving communication, Caballero suggested, is an important part of ensuring adequate healthcare to ethnic minorities. However, what is needed is not only translation from English to other languages. He pointed to examples in which different populations comprehend the same message in different ways, suggesting that translation must also be aware of cultural nuances between ethnic groups. Caballero cited a list of other cultural factors that may influence diabetes development and care, such as nutritional preferences, alternative medicine, religious practices, or belief in health care myths.
While acknowledging that discrimination is rarely intentional, Caballero advised that providers need to become more familiar with the cultural issues relevant to the populations they serve. They should also be trained to learn the tools and skills needed to provide quality care to any patient, regardless of race, ethnicity, culture, class, or language proficiency. In other words, they need to develop cultural competence, or an awareness and acceptance of cultural differences (e.g., beliefs about illness or alternative medical practices), and adapt their skills accordingly. The critical component, Caballero said, is awareness.
It is estimated that more than 23 million Americans are diabetic. Nearly one quarter of those remain undiagnosed, in part because they are uninsured or otherwise disadvantaged. In the United States, type 2 diabetes is disproportionately more common in ethnic minorities, including African American, Native American, Hispanic/Latino, Asian, and Pacific Islander populations, than in their non-Hispanic, white peers. Minorities also have higher rates of complications and co-morbidities such as coronary artery disease or stroke. In addition, even when access to care is comparable, disparities persist in the quality of diabetes care that is provided to minority patients.
On September 15, 2009, the Academy convened experts in diabetes, metabolism, endocrinology, epidemiology, and cardiology, to discuss disparities in the incidence and treatment of type 2 diabetes and associated comorbidities and complications.
In the first session, Enrique Caballero provided an overview of the biological, social, and cultural factors that influence the health disparities observed in diabetes.
In the second session, Harold Lebovitz described the genetic and metabolic factors associated with cardiovascular risks and complications in patients with diabetes. Guillermo Umpierrez then expanded on the cultural barriers that impact the quality of care minorities receive, and Lawrence Young discussed the role of specialized cardiac screening in diabetic patients without cardiac symptoms.
In the third session, Elizabeth Walker presented an overview of the New York City Department of Health's Hemoglobin A1c Registry, and an associated study comparing follow-up with diabetic patients by letter versus phone call, with regard to improving glycemic control. Finally, Ann Albright discussed the public health approaches underway at the U.S. Centers for Disease Control and Prevention (CDC) to address diabetes disparities.
Harold E. Lebovitz, State University of New York Health Science Center at Brooklyn
Guillermo E. Umpierrez, Emory University School of Medicine
Lawrence H. Young, Yale University
- More than 30 genes have been identified that are associated with the development of type 2 diabetes.
- Insulin resistance is directly related to visceral fat levels, and leads to a metabolic syndrome and premature beta cell death in those who are genetically predisposed.
- Most diabetic patients present with multiple comorbidities. Four factors that must be addressed together are blood glucose, blood pressure, lipid profile, and obesity/overweight.
- Coronary artery disease is the primary cause of mortality in patients with type 2 diabetes.
- Overall, the challenges of generalized screening for coronary artery disease in asymptomatic patients with type 2 diabetes outweigh the benefits. Rather, the focus should be on primary prevention strategies, patient education, and close clinical follow-up.
Who is at risk?
Type 2 diabetes is not a single disease, said Harold Lebovitz of SUNY Health Science Center at Brooklyn. To date, more than 30 genes have been identified that are associated with the development of diabetes. Mutations in these genes lead to disturbances in metabolic regulation, and patients can have a variety of different genetic abnormalities.
Lebovitz expanded upon the association of obesity and inflammation introduced by Enrique Caballero. He explained that adipocytes (fat cells) secrete a variety of bioactive substances that modulate insulin resistance and cardiovascular risk, including: immune modulators such as TNF-α and other cytokines; adiponectin, which controls insulin sensitivity; cardiovascular modulators that affect thrombosis; and hormones that influence appetite. Excess adipose tissue attracts monocytes and macrophages, and initiates a systemic inflammatory process.
An important finding is that all fat is not the same. The metabolism and biochemistry of visceral fat cells is different from that of subcutaneous fat cells, and people with the same body mass index (BMI) can have different percentages of visceral fat. Lebovitz cited a study showing that increased visceral fat is associated with an increase in insulin resistance; however, the amount of subcutaneous fat does not impact insulin action. As a result of its impact on insulin resistance, excess visceral fat can lead to a metabolic syndrome that puts the individual at greater risk for cardiovascular disease, diabetes, and non-alcoholic fatty liver disease (NAFLD).
Where an individual stores fat appears to be genetically determined to some extent. Comparing individuals of the same BMI, African Americans have less visceral fat than any other group, but there is no difference in subcutaneous fat. While obesity is generally a factor in diabetes, African American males who are lean, or mildly overweight, still have a much higher rate of diabetes than white males with similar BMI. The reasons why insulin resistance appears to manifest differently in African Americans are not yet known.
Hepatic triglyceride levels (i.e., the amount of fat in the liver) are proportional to visceral fat. As such, African Americans are much less likely to have NAFLD than Hispanic or white individuals. They also do not have the same degree of atherogenic dislipidemia as other populations, and this is perhaps the reason why there is less atherosclerotic heart disease in African Americans. Still, African Americans have higher rates of hypertensive heart disease, and have a higher overall mortality rate from heart disease than do other populations. African American and other minority men also show signs of heart disease at younger ages than white males.
Asian Indian men have more insulin resistance and fatty liver disease than other ethnic populations, Lebovitz noted. Muscle mass is low, body fat is high, and they have a greater propensity to put down visceral fat, leading to a higher prevalence of diabetes and coronary artery disease.
Metabolic differences between populations must be taken into account when considering treatments.
Clearly, there are metabolic differences between populations that must be taken into account when considering treatment for patients. For white and Hispanic patients, providers should be focused on lipid levels and cardiovascular risk reduction. For African Americans, drugs to treat insulin resistance may be more appropriate.
At its most basic, diabetes is a disease of the beta cells (pancreatic cells that make and secrete insulin). Some people are genetically predisposed to lose beta cells at an increased rate, but most people who are of normal weight and active will still have enough viable beta cells to last a lifetime. In the diabetic who is predisposed to increased beta cell loss, increased visceral fat leads to insulin resistance and a metabolic syndrome that causes the beta cells to die even more rapidly.
In summary, Lebovitz said, the primary goal should be prevention. To prevent diabetes we need to prevent central obesity, and thereby prevent insulin resistance and the metabolic syndrome. Once diabetes is diagnosed, insulin resistance must be treated to stop the cascade. If the metabolic syndrome can be eliminated, we can decrease diabetes and decrease cardiovascular disease, which is the primary cause of death in diabetics.
What can we do?
One out of three Americans has cardiovascular disease, said Guillermo Umpierrez of Emory University, but the prevalence of the particular type of cardiovascular disease varies by race and ethnicity. Over the past ten years there has been an overall trend toward decreased blood pressure, glucose, and cholesterol levels in individuals with both cardiovascular disease and diabetes. However, disparities based on racial, ethnic, or socioeconomic differences persist. Patients with diabetes have a risk of micro- and macrovascular complications including retinopathy of the eye, end-stage renal disease, and lower extremity amputations, all of which occur more frequently in minorities. Umpierrez cited two meta-analyses that showed that HbA1c levels are significantly higher in diabetic African Americans and Hispanics, than in non-Hispanic whites, regardless of sex, suggesting that higher HbA1c may be related to the increased rate of complications.
Although Latinos have higher baseline HbA1c levels, response to therapy is similar to that of African Americans and whites, and after 6 to 12 months on therapy, there is no difference. While this is promising, therapy and follow-up requires access to care. Umpierrez's research shows that at Grady, the largest healthcare system in Atlanta, appointment keeping seems to vary by ethnicity. More than 40% of African American and white patients return for follow-up appointments after 12 months, but less than 25% of Latinos return. Getting these patients to come back for subsequent appointments is critical to the success of their diabetes management. To help address this issue, Grady set up neighborhood satellite clinics to enable Latinos to return for follow-up appointments without having to travel downtown to the hospital. Disparities in health insurance coverage are also well established, Umpierrez said, and increasing the number of patients with insurance is essential.
Normalizing HbA1c level, while important, will not solve the diabetes crisis or eliminate disparities. Most patients present with multiple comorbidities. Several studies have shown that addressing glycemic control alone does not decrease mortality. In diabetic patients, African Americans especially, blood pressure should be a primary concern. Improving blood pressure control will decrease micro- and macrovascular complications, and mortality in general. Treating blood pressure may be as, or more effective in decreasing some of the complications of diabetes, compared to glycemic control.
To reduce cardiovascular morbidity and mortality in diabetic and non-diabetic patients, Umpierrez stressed the need to increase access to care, including drug benefit programs; increase access to educational programs; and improve cardiovascular risk factors by managing blood glucose, blood pressure, lipid profile, and obesity/overweight.
Is screening the answer?
The risk of cardiovascular disease is two- to four-fold higher in diabetics. Routine management of cardiac risk factors in asymptomatic patients with type 2 diabetes generally focuses on lowering cholesterol and controlling hypertension and glucose levels. Lawrence Young of Yale University posited whether there is a role for cardiac screening to further prevent cardiac events. Screening, Young clarified, is specialized cardiac testing to detect asymptomatic coronary atherosclerosis or inducible ischemia. Screening is limited to patients without known or suspected coronary artery disease based on symptoms, physical exam, and resting ECG (i.e., screening is not diagnostic testing in those with symptoms, or risk stratification of those with known coronary artery disease. Such patients warrant immediate evaluation.) The primary rationale for screening is to prevent myocardial infarction, heart failure, or death. Clinical researchers thought that screening could improve surveillance by physicians, could lead to coronary intervention in high-risk individuals, and that providing screening results to patients could enhance compliance with primary prevention strategies.
To better understand the potential of cardiac screening in diabetic patients, the Detection of Ischemia in Asymptomatic Patients with type 2 Diabetes (DIAD) study was undertaken. The study set out to assess the incidence of cardiac events in contemporarily treated patients, the clinical predictors of adverse cardiac outcomes, the prevalence of asymptomatic coronary artery disease and inducible ischemia, how well screening predicts adverse cardiac outcomes, and whether screening changes therapy to improve outcomes.
DIAD was conducted as a multi-center trial of over 1100 patients with type 2 diabetes, and without any history or signs of coronary artery disease. Patients were randomized to either a screening group that underwent myocardial perfusion imaging ("stress test"), or a standard-of-care group that wasn't tested. Of the screening group, 22% had abnormal cardiac test results. Predictors of very abnormal results were male gender, BMI>30, and cardiac autonomic dysfunction. After 5 years, the study results indicated that the overall cardiac event rate was 3%, with no significant difference observed between the screening and standard-of-care groups with regard to cumulative mortality, primary endpoints (cardiac death and acute, non-fatal myocardial infarction), or secondary endpoints (including unstable angina, heart failure, stroke, or revascularization). Simply put, screening did not improve outcome.
As noted above, one rationale for screening was that results indicating a higher risk would foster patient compliance with medication use. The results of the DIAD study showed no difference in medication compliance between the two groups at study start, or at follow-up 5 years later. Young suggested that the relationship between physician and patient is likely more effective in fostering patient compliance than a test result.
The challenges of screening nonsymptomatic patients outweigh the benefits. Primary prevention, patient education, and clinical follow-up are the keys to reducing risk.
Proponents of screening have argued that the DIAD study was not a representative cohort and was selective for low risk patients. Indeed the inclusion criteria required no history of coronary artery disease or cardiac symptoms, no ischemic ECG changes, and favorable glycemic control and lipid levels. However, the cohort was also middle-aged with established diabetes and obese (average BMI of 31). Thirty-four percent reported they were inactive, 50% were unable to exercise, 22% were taking insulin, and 60% had more than two risk factors.
Young highlighted several issues with the conduct of specialized screening, including costs, false positive tests leading to unnecessary procedures, and problems with insurability and employment. Cardiac events also occur in patients without inducible ischemia (i.e., who did not have positive screening test results). In addition, severe coronary artery disease is relatively infrequent and not always amenable to revascularization. And revascularization is not clearly beneficial in patients with mild to moderate disease.
The overall conclusion, Young said, is that the challenges outweigh the benefits, and screening should not be recommended for the general population of asymptomatic patients with type 2 diabetes. Instead, primary prevention strategies, patient education, and close clinical follow-up remain the key components of risk reduction efforts.
Elizabeth Walker, Albert Einstein College of Medicine
Ann Albright, Centers for Disease Control and Prevention
- The New York City Department of Health has begun a pilot program to assess the potential of the existing public health surveillance system for tracking and controlling the diabetes epidemic.
- In addition to tracking diabetes in the city, the registry program provides patients and providers with tools, resources, and education to assist in prevention and management of the disease.
- Patients with high HbA1c levels receive a letter encouraging them to visit their doctor. An ongoing study is comparing the effect of this standard print communication to periodic telephone calls to see if interactive phone communication improves glycemic control among diabetics in the South Bronx.
- There have been modest population-level improvements in preventive care and diabetes outcomes, but all individuals are not experiencing the same benefits and improvements.
- Interventions and resources must reach those who need them, but patients must also understand how to use them, otherwise they are of little value.
Just a phone call away
One in eight people in New York City (12.5%) has diabetes, said Elizabeth Walker of the Albert Einstein College of Medicine. The Bronx is among the boroughs with the highest prevalence of diabetes in the city, and the prevalence in the South Bronx is nearly 17%. Ninety-four percent of residents of the South Bronx are Hispanic or African American, and 82%–90% report a household income at or below 200% of the federal poverty level. The New York City Department of Health concluded that prevalence of diabetes and complications in the city was high, and control of HbA1c and risk factors for complications was "mediocre at best." Thus, they decided to explore the traditional public health surveillance system as a means to track and control the diabetes epidemic. With Board of Health approval, the City established the A1c Registry, the first of its kind, and chose the South Bronx for the pilot program.
As mandated by a revision to the local health code, all 39 laboratories serving New York City are required to report HbA1c test results, regardless of diabetes diagnosis. The electronic system is based on the existing laboratory reporting infrastructure for communicable diseases, which eliminates the need for paper reporting, and does not rely on provider reporting. The registry receives around 100,000 test results per month, and since its inception in 2006, has amassed around 4.8 million test results for 2 million individuals.
Programs target health disparities in the South Bronx in a culturally sensitive manner.
A goal of the registry program is to develop tools to support providers and patients. For example, letters are sent out encouraging patients with high HbA1c test results to visit their physician. The data from the registry are also used to target resources where they are needed most across the five boroughs. For example, parks and recreation memberships are available for providers to give to patients to foster exercise. The registry also functions for surveillance and epidemiology, and can be used to increase awareness in the community.
The Einstein Diabetes Research and Training Center and the NYC Department of Health have recently partnered for an NIDDK-funded translational research study, the "Bronx A1c: Bring it Down for Health" study; Dr. Walker is the principal investigator. This randomized controlled trial is comparing telephonic intervention with print intervention to improve glycemic control among adults with diabetes in the South Bronx. The focus of the study is self-management support, and is based on the hypothesis that providing self-management support to patients and decision support to providers will foster improved outcomes.
Walker cited the results of three preliminary studies that support the premise of the current study. The Diabetes Prevention Program showed that medication adherence can be promoted in a large study. The Vision is Precious study aimed at fostering dilated eye exams with a telephone intervention, and the Improving Diabetes Outcomes study, aimed at improving medication adherence, physical activity and healthy eating, suggest that receiving information by telephone is more effective than printed material by mail for supporting patient behavior change and outcomes.
For the standard intervention, participants are managed as per the protocol of the A1c registry (e.g., receive a letter if their HbA1c is >9%, receive resources from their physician). The telephonic intervention group receives the standard intervention plus: if their HbA1c is >7%–9%, the patient receives up to 4 phone calls in 12 months; if HbA1c is >9%, the patient receives up to 8 calls and a letter to their provider after 6 months relaying patients' concerns about barriers to glycemic control. Bilingual health educators discuss problem solving, goal setting, medication adherence, healthy eating and physical activity, help patients to achieve improved communication with medical providers, and assist them with navigating the health system.
The goal is to overcome health disparities by reaching out to urban poor populations, offering behavioral interventions in a culturally sensitive manner, and training bilingual health educators from the community. The target population is people who may not be able to travel to an appointment (e.g., they work two jobs or seven days a week), but who would have time to talk by phone periodically. The study hopes to achieve improved diabetes control in a large number of people, and if successful and costs are reasonable, facilitate rapid scale-up of the intervention across New York City.
Envisioning a world free of the devastation of diabetes
Ann Albright of the Centers for Disease Control and Prevention (CDC) wrapped up the meeting with an overview of the public health approaches being used by CDC to address diabetes health disparities. The Division of Diabetes Translation at CDC is focused on reducing the preventable burden of diabetes through public health leadership, partnerships, research, programs, and policies that translate science into practice. The Division works to define the diabetes burden through public health surveillance and conducts applied translational research to prioritize effective interventions. Efforts are concentrated where the greatest impact can be achieved for populations with the greatest burden or risk.
The prevalence and incidence of diagnosed diabetes has increased rapidly, particularly since the 1990s, in part because of a change in the diagnostic criteria. Prevalence is the number of people with a given condition at any given time. Incidence is the number of new cases. It is important to remember, Albright noted, that in diabetes, prevalence can go up not just because there is an increase in incidence (new cases), but for positive reasons as well, including changes in diagnostic criteria, enhanced case detection, or decreased mortality.
While most diabetes surveillance is conducted on adults, CDC is conducting a large surveillance study on diabetes in youth. Type 1 is the most common form of diabetes in children aged 0–9 years, and for the majority of 10–19 year olds as well. However type 2 is now the predominant form in Native American youth aged 10–19 years, and is increasing in prevalence in African American youth.
National surveys show that there have been modest to moderate population-level improvements in preventive care (e.g., foot exams, eye exams, aspirin use) over the past decade. However, even though the trend is toward overall improvement, there are still populations that are not receiving proper preventative care. Similarly, intermediate outcome measures, such as blood pressure and HbA1c levels, have decreased over time, but the greatest improvements are observed in the highest 25% of income level. There have also been reductions in distal outcomes, such as vision loss, amputation, end-stage renal disease, cardiovascular disease, total hospitalizations, and mortality rates. These results are derived from population-based surveys, and while there is progress in the right direction, Albright stressed that not everyone is experiencing these same benefits and improvements, and there is still more to be done to ensure all patients receive quality care.
Albright highlighted several areas of ongoing concern, including the persistence of disparities in diabetes complications in African American, Native American, and Latino patients, and the growing burden of disease in youth and young adults. In addition, the pace of progress made in risk factor improvement, especially blood pressure reduction, has slowed.
Albright laid out the steps to success, from basic science through to the scale-up and distribution of treatments and interventions. She noted that the efficiency step is important for addressing disparities, trying to determine what mix of interventions will have the greatest effect on the health of the most people. Availability and distribution are also very important. The discoveries and tools must reach those who need them, and patients must understand how to use them, otherwise they are of little value. Policy has a significant role to play in these three steps. Albright noted that while there are always concerns that there is not enough investment in basic research, there is even less investment in each successive step.
In summary, Albright said that we must sustain and build on the gains made in diabetes control, and build and expand primary prevention efforts. The National Diabetes Education Program co-sponsored by CDC and NIH now has more than 100 materials and tools supporting public health efforts toward diabetes prevention and control.