Diabetes and Heart Disease
The Diabetes Epidemic
The prevalence of diabetes is increasing worldwide. The World Health Organization predicts that if current trends continue the number of persons with diabetes will more than double, from 140 million to 300 million in the next 25 years. In the US, diabetes affects nearly 16 million people, and the prevalence of diabetes has increased by 33% in adults over the last 10 years. About 800,000 new cases of diabetes are diagnosed in the US each year.
The greatest increase in diabetes is in non-white portions of the population. The increase of diabetes in Hispanic Americans was 38% and 26% in African Americans. According to the US Office of Minority Health, the prevalence of diabetes in blacks is about 70% higher than in whites in the US, and the prevalence in Hispanics is nearly double that of whites. And the rate of diabetes in Native Americans and Alaska Natives is more than twice that for the total US population.
The Centers for Disease Control (CDC) estimates from 1998 were that 10.8% of African American adults (aged 20 and older) have diabetes: 2.3 million people. An estimated 10.6% of Hispanic Americans (1.2 million people) have diabetes. Prevalence among Non-Hispanic whites is estimated at 7.8%, and 9.8% in Native Americans. And these numbers do not include the growing numbers of diabetic children and teenagers.
Studying the Effect of Diabetes on the Heart
Diabetes is the 7th leading cause of death in the US, and heart disease is the leading cause of diabetes-related deaths. According to the CDC, adults with diabetes have heart disease death rates about 2 to 4 times as high as that of adults without diabetes. They also have a 2-4 times higher risk of stroke. In 1996, about 43% of all diabetes-related deaths in the US had heart disease or stroke as the underlying cause of death.
Diabetes is at near epidemic proportions among blacks, according to William Chilian, PhD, formerly a Professor of Physiology at the Medical College of Wisconsin. Diabetes increases the mortality of blacks with heart disease by more than three times compared with more widely recognized heart disease risk factors like high blood pressure, smoking, high cholesterol and obesity.
Dr. Chilian and David D. Gutterman, MD, Professor of Medicine (Cardiovascular) at the Medical College, and their colleagues Clarence Grim, MD, Clinical Professor of Medicine (Cardiovascular), and John Baker, PhD, Associate Professor of Pediatric Surgery, are embarking on a five-year program of research to better understand -- and eventually prevent -- the cardiovascular complications in blacks with non-insulin-dependent diabetes.
Their research, funded by the National Institutes of Health, encompasses four related projects. The first is aimed at understanding why diabetes inhibits the growth of new blood vessels in the heart. "Many of the manifestations of heart disease are much worse in patients who grow these vessels poorly," Dr. Chilian says. "Our research might help us understand why diabetic patients have much worse outcomes after they've had a heart attack." These small vessels are known as collateral blood vessels. Dr. Chilian's work will focus on biological substances called growth factors that control the growth of blood vessels. Dr. Chilian wants to find out how diabetes interferes with the way these growth factors function.
The second project will ask whether there is a genetic reason behind the failure of these collateral blood vessels to grow. "Is there some gene that has been mutated in all patients?" he asks.
Because some blacks are at far greater risk than whites for non-insulin-dependent diabetes, the researchers will be attempting to see if there are racial differences involved. They will compare blacks in Milwaukee, Wisconsin, with a white population in Germany. The German work is being done in collaboration with the University of Regensberg, which has available a unique data set of 900 German siblings who have coronary artery disease and have had angiograms. Black participants in the study will be drawn from the Milwaukee Cardiovascular Data Registry after obtaining their consent. Froedtert Hospital and the Clement J. Zablocki VA Medical Center have agreed to participate in this process.
The focus of the third project will be to discover whether there is a racial difference in what are known as resistive arteries. "These are normally the ones that decide how much blood flow the heart is getting and where that flow is going," Dr. Chilian says. "They act as stoplights."
The fourth project will use rats to study the genetics behind the heart's ability to withstand a stoppage of blood flow. "Let's say there is a blood vessel growth factor that is inhibited in diabetics," Dr. Chilian explains. "Then we could treat people with that growth factor, or treat people with genetic therapy to restore that growth factor." Because of the genetic similarity between rats and humans, when the researchers identify these genes in rats, they hope eventually to develop therapies to treat diabetics or make the heart resistant to a heart attack. Article Created: 2001-01-29
Article Updated: 2001-12-07
MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.
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