February 6, 2002
Monica Boone, a soft-spoken silversmith and mother of two from Zuni, New Mexico, was haunted by a fear of diabetes. It had killed her father, who died of a diabetes-induced heart attack at age 57, and one of his brothers. Another uncle on her father's side now struggled with the disease. She figured she was next in line. At 5 feet 3 inches tall, she weighed 173 pounds, had little energy and didn't get much physical activity. So 3 years ago she looked into a research study getting under way in Zuni. She entered the study when her tests came back showing she had impaired glucose tolerance (IGT), a condition one step away from diabetes.
In IGT, which affects about 20 million people in the United States, blood glucose levels are higher than normal but not yet diabetic. Having IGT sharply raises the chances of developing type 2 diabetes and heart disease. Once a person develops type 2 diabetes, the risk of heart disease is even higher-2 to 4 times that of people without diabetes.
"I was scared for myself and my family, but I still wanted to know where I stood," she recalls. "When I found out about the study, I felt I was being given a second chance. I decided to take that chance. I wanted to help them find out if this disease can be prevented."
Boone, like thousands of other adults across the country at high risk for type 2 diabetes, had joined a research study called the Diabetes Prevention Program (DPP). Everyone in the study had IGT and was overweight. Volunteers were randomly assigned to one of the following groups:
- Lifestyle changes: aim to lower body weight by 7 percent by lowering intake of fat and calories and exercising 150 minutes a week at moderate intensity. (Most chose walking an average of 30 minutes a day 5 days a week.)
- Metformin: take 850 milligrams of the oral diabetes drug metformin (Glucophage) twice a day. This group also got information on diet and exercise.
- Placebo: take placebo pills in place of metformin. This group also got information on diet and exercise.
As a study volunteer, Boone was randomly assigned to lifestyle changes. She needed to lose 7 percent of her weight-about 12 pounds-by curbing fat and calories in her diet and exercising 150 minutes a week. Boone decided to walk. Her first time out was tough. "My heart was beating so fast," she recalls. Slowly, she built up her endurance from 1 mile to 2, then 3, then 4 miles at least 5 days a week. She gradually mixed in jogging with walking. She ate fewer fast foods and began cooking nutritious meals at home. The weight started to drop off. In time she lost 20 pounds. Best of all, her blood glucose levels went back to normal.
Boone was one of the 3,234 DPP participants who helped prove that diet and moderate exercise can sharply delay and possibly prevent type 2 diabetes. Specifically, diet and exercise resulting in a 5- to 7-percent weight loss lowered the incidence (development of new cases) of diabetes by 58 percent. The same study found that the drug metformin cut the incidence of type 2 diabetes by 31 percent.
And the good news didn't end there. While both interventions lowered fasting blood glucose levels, diet and exercise were more effective at lowering blood glucose levels 2 hours after a glucose drink. Also, about twice as many people in the lifestyle group compared to those who got standard advice regained normal glucose levels, showing that diet and exercise can reverse IGT.
Researchers announced results of the trial last August after ending the study a year early. Their findings are reported in the February 7 issue of the New England Journal of Medicine.
"This research conveys a powerful message of hope to people at risk for type 2 diabetes, a painful, life-threatening disease that has been increasing in this country along with obesity," said Health and Human Services Secretary Tommy G. Thompson. "By adopting a moderate, consistent diet and exercise program, many people with one or more of the risk factors for type 2 diabetes can stop the disease before it becomes irreversible."
Nearly half of the DPP participants were from minority groups that suffer disproportionately from type 2 diabetes: American Indians, African Americans, Hispanic Americans, Asian Americans, and Pacific Islanders. Diabetes has hit American Indians harder than any other ethnic group in the United States, taking an enormous toll in pain, disability, and loss of life. On average, American Indians and Alaska Natives are 2.6 times mores likely to have diabetes than non-Hispanic whites of similar age.
"Lifestyle intervention worked equally well in men and women and in all ethnic groups. It was most effective in people age 60 and older, who lowered the risk of developing diabetes by 71 percent. Metformin was also effective in both sexes and in all the ethnic groups. However, it was relatively ineffective in older volunteers and in those who were less overweight," said study chair Dr. David Nathan of Massachusetts General Hospital, Boston.
Dr. William Knowler, a researcher with the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the part of the National Institutes of Health that sponsored the trial, oversaw the study at five urban and reservation communities in the Southwest. "Study participants from American Indian communities helped prove that type 2 diabetes can be delayed in many people at high risk. By adopting healthy diet and exercise habits, individuals can do a great deal to lower the risk of diabetes and add immeasurably to their overall health and quality of life," said Dr. Knowler, who has for years worked to find the causes of type 2 diabetes in the Pima Indians near Phoenix, Arizona.
"What floored us was how quickly diet and exercise made a big impact in reversing the slide into diabetes," said Mary Hoskin, the coordinator of the clinical trial in Arizona. "In just 3 years, diet and exercise resulting in a modest weight loss of, say, 10 or 15 pounds made such a big difference in health."
"The research was done in our communities, and it's already making a big difference here. We contributed to this study, and we are benefiting from it," added Shandiin Begay, a member of the Navajo Nation who works closely with participants in three Indian communities in Arizona. "The lifestyle changes the participants made helped not only themselves but their families and communities. This study shows that we can change the future of diabetes in Indian country."
Other research has shown that diet and exercise delay type 2 diabetes in at-risk people, but the DPP, conducted at 27 centers nationwide, is the first major study to show that lifestyle changes can delay diabetes in a diverse population of overweight American adults with IGT. It is also the first major study to look at whether a drug could help lower diabetes risk.
"We're in an all-out war against diabetes," said Merna Lewis, vice president of the Salt River Pima-Maricopa Indian Community, who called the findings "tremendous." "Of course, we were hoping for something miraculous to come along, but it all boils down to what we suspected before: diet and exercise are the key. Now we are educating people in how to prevent this disease. We're taking the message of exercising and eating healthy foods into schools and childcare centers because even our young people are getting diabetes. We've started bi-weekly classes in cooking nutritious meals, and we're encouraging exercise in everyone, clear up to seniors."
Mrs. Lewis, a dynamic leader who struggles with diabetes herself, strongly supported the study from the beginning. "Do everything you can to avoid getting diabetes," she counsels young people. "Don't say 'I'm going to get it anyway. If it comes, it comes.' And if you already have diabetes, don't give up. People feel angry and discouraged. They say 'how come me?' The problem is, diabetes can hit anybody, even young children, who will have to deal with it a long time," she says.
"Attitude is everything," she adds. "It's really up to you whether you want to live longer or just give up."
Can lifestyle changes or metformin treatment prevent diabetes completely? "We just don't know how long, beyond the 3-year period studied, diabetes can be delayed," says Dr. Nathan. "We hope to follow the DPP volunteers to learn how long the interventions are effective." The researchers will analyze the data to determine whether the interventions reduced heart disease and atherosclerosis, major causes of death in people with type 2 diabetes.
About 16 million people in the United States have diabetes. It is the main cause of kidney failure, limb amputations, and new cases of blindness in adults and a major cause of heart disease and stroke. Type 2 diabetes accounts for up to 95 percent of all diabetes cases. Most common in adults over age 40, type 2 diabetes affects 8 percent of the U.S. population age 20 and older. It is strongly linked to obesity (more than 80 percent of people with type 2 diabetes are overweight), inactivity, family history of diabetes, and racial or ethnic background. The prevalence of type 2 diabetes has tripled in the last 30 years, due in large part to the upsurge in obesity.
Behind Monica Boone's house are the trails she runs and has come to love, paths that wind through a valley surrounded by the stark beauty of Corn Mountain and the Bluebird Mesas. She's gone through 10 pairs of running shoes. "I look forward to my runs now," she says. "I see small animals like rabbits and rodents and beautiful birds, even a golden eagle sometimes. I have more energy, I'm quicker in my movements, and I enjoy going here and there. I used to dread it. People say 'Is that you?' They don't recognize me," she laughs.
"If you love yourself, it's worth the time it takes," says Boone. "Taking one hour out of 24 for yourself is not a very big sacrifice."
The DPP was funded by the National Institutes of Health as well as the Centers for Disease Control and Prevention and the Indian Health Service, all HHS agencies. It also received funding from the American Diabetes Association. Sources of corporate support included Bristol-Myers Squibb, Parke-Davis, Merck and Company, Merck Medco, Hoechst Marion Roussel, Sankyo, Lifescan, Slimfast, Nike, and Health-O-Meter.
NIDDK (301) 496-3583