© Geriatric Times. All rights reserved.
Lifestyle Changes Can Reduce Incidence of Type 2 Diabetes
by Maury Breecher, Ph.D.
Geriatric Times March/April 2002 Vol. III Issue 1
Physicians have long noted the connection between obesity and a sedentary lifestyle and the development of diabetes. Results of a landmark study published in The New England Journal of Medicine indicated that the estimated 10 million Americans now at risk for type 2 diabetes can sharply lower their chances of getting the disease by losing 7% of their weight and walking 30 minutes a day, five days per week (Diabetes Prevention Program [DPP] Research Group, 2002).
Metformin's (Glucophage) effect on the incidence of diabetes was also part of the study's design. The researchers found the combination of losing weight and exercising consistently was almost twice as effective as the medication. They concluded, "Metformin and modification of lifestyle were two highly effective means of preventing type 2 diabetes. The lifestyle intervention was particularly effective with one case of diabetes prevented per seven persons treated for three years." Nearly 14 people would have to receive metformin for three years to prevent one case of diabetes. (DPP Research Group, 2002).
The Diabetes Prevention Program
Twenty-seven medical centers in the United States participated in the three-year DPP. All 3,234 participants were at high risk for diabetes and had impaired glucose tolerance levels. They were randomized to standard lifestyle recommendations plus either placebo or metformin (850 mg twice a day) or an intensive lifestyle modification program with two goals for participants: 7% reduction of their weight and 150 minutes of moderately intense physical activity per week.
Previous studies in Sweden (Eriksson and Lindgärde, 1991), China (Pan et al., 1997) and Finland (Tuomilehto et al., 2001) had indicated that changes in diet and in exercise habits might delay the onset of diabetes. Methodologic weaknesses in some of these earlier studies and uncertainties about whether interventions that worked in other countries could actually work in the United States (Tataranni and Bogardus, 2001) led to the DPP.
Those uncertainties exist no more.
The results from the DPP (Figure) were so striking that the clinical trial ended early to enable people in the placebo arm to benefit from the findings, explained Nathaniel Clark, M.D., national vice president of clinical affairs of American Diabetes Association (ADA).
"The group that [made lifestyle modifications,] lost 10 pounds and walked approximately 30 minutes a day, five days a week, had a greater than 50% reduction in their risk of developing diabetes," Clark told Geriatric Times.
In fact, compared to the placebo group, the subjects randomized to the lifestyle change reduced their chances of developing type 2 diabetes by 58%. The individuals in the metformin group had only a 31% reduction in risk.
Initially, the DPP also had a group of subjects who were prescribed troglitazone (Rezulin). That arm of the study was discontinued after troglitazone was taken off the market and one of the participants died from liver problems, complications that may have been caused by the now-withdrawn drug.
Anne L. Peters, M.D., director of clinical diabetes services and a professor of clinical medicine at University of Southern California's Keck School of Medicine, told GT that unpublished data from the troglitazone arm of the study indicated that individuals who took that drug received "a great deal of protection against early onset of diabetes. It is an indication that other glitazones may also offer diabetes prevention benefits."
Clark said there have been no multicenter studies that have looked at the diabetes prevention benefits of rosiglitazone (Avandia) or pioglitazone (Actos), the other glitazones. The ADA recommends that individuals with impaired glucose tolerance that has not yet progressed to type 2 diabetes be put on medication only after lifestyle changes, including diet and exercise, are tried first.
"The ADA is currently working on position statements…that will incorporate what was learned from the DPP [and similar investigations]. The advice will be that lifestyle intervention is the way to go," he continued.
A similar investigation--the largest and most comprehensive study on diabetic risk factors in women--looked at the diet and lifestyle choices of 84,941 nurses. This study concluded, "The majority of cases of type 2 diabetes could be prevented by weight loss, regular exercise, modification of diet, [and] abstinence from smoking and the consumption of alcohol" (Hu et al., 2001).
Is a National Prevention Program Needed?
These studies all seem to point to the need for a national diabetes prevention program. Some physicians, including Peters and Yehuda Handelsman, M.D., head of the section of endocrinology and metabolism at the Tarzana Regional Medical Center in Tarzana, Calif., also believe we need one aimed especially at children.
"We should have a national diabetes prevention program--at least one in the schools aimed at children," Handelsman told GT. "We have an epidemic of obesity contributing to an epidemic of diabetes and heart disease. Type 2 diabetes is occurring in children as young as 8, 9 or 10. It is not unusual to see a heart attack in a child as young as 15 years old anymore."
Peters added, "It makes sense to have a national preventive program, especially if it is aimed at people at high risk."
Clark, however, was doubtful about the cost-effectiveness of a national program. "The message of changing your lifestyle by losing weight and by exercising is certainly a message that we want people with type 2 diabetes to get," he said. "However, the success rate of people continuing to adhere to diet and exercise is very poor…The study organizers had to go to great lengths to convince people to continue their exercise and dietary changes."
Participants in the DPP intensive lifestyle intervention had the benefit of a 16-lesson curriculum covering diet, exercise and behavior modification, which had to be completed during the first 24 weeks. The lessons were taught by case managers on a one-to-one basis, and participants received frequent contact from someone on the team, either a dietician, nurse, physician or exercise trainer.
Clark explained, "They were provided gym memberships and some were even given home exercise equipment or put into contact with personal trainers. They were really encouraged in every way possible."
Fifty percent of the participants in the lifestyle intervention group achieved the goal of a 7% or more weight loss by the end of the 24-week curriculum. However, only 38% had a weight loss of at least 7% at the time of the most recent visit by study investigators (two and a half years after finishing the 16-lesson curriculum).
"The challenge for the future of the DPP is whether we can find more cost-effective, lasting interventions that will have as good results," said Clark.
The benefits are well worth it, according to Peters and Handelsman. Each pointed out that preventing diabetes also prevents cardiovascular complications, including stroke and myocardial infarction.
"The new research underscores the need for primary physicians to aggressively screen for type 2 diabetes and, once discovered, to treat it assertively from its earliest stages," said Handelsman.
He cited the United Kingdom Prospective Diabetes Study (UKPDS) finding that for every percentage point decrease in blood glucose as measured by the hemoglobin A1c (HbA1c) test, there was a 35% reduction in the risk of microvascular complications (ADA, 2002).
The UKPDS study also revealed that "tight blood pressure control, consistent with ADA recommendations, significantly reduced virtually all cardiovascular and microvascular outcomes including strokes, diabetes-related deaths and heart failure," said Handelsman. "That is important in light of the fact that atherosclerotic cardiovascular disease (CVD) is the most important cause of morbidity and mortality in patients with diabetes" (Goldberg and Capuzzi, 2001).
Thus vigorous treatment of diabetes through lifestyle changes and/or medications not only decreases the morbidity and mortality of diabetes, but also decreases cardiovascular morbidity and mortality by reducing blood pressure and encouraging better lipid profiles, according to Handelsman.
Peters agreed: "The DPP only lasted three years so we don't know if lifestyle modification or drug treatment would continue to have long-term benefits. However, we know that the rate of obesity is increasing in both adults and children. For that reason, I feel that if we prevent diabetes from occurring, or even if we just slow its onset, we are doing a good thing.
"The longer a person has diabetes, the more they are at risk for complications," she continued. "If we started working at prevention earlier with children and young adults, I believe the lifelong benefits would be tremendous, especially to those with impaired glucose tolerance who have a very high risk of developing type 2."
In a press release announcing the results of the DPP, Allen Spiegel, M.D., director of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), which sponsored the study, said, "Every year a person can live free of diabetes means an added year of life free of the pain, disability, and medical costs incurred by this disease. The DPP findings represent a major step toward the goal of containing and ultimately reversing the epidemic of type 2 diabetes in this country" (NIDDK, 2001).
"We simply don't know how long, beyond the 3-year period studied, diabetes can be delayed," said DPP study chair David Nathan, M.D., of Massachusetts General Hospital, in the same press release. "We hope to follow the DPP population to learn how long the interventions are effective" (NIDDK, 2001).
Preventing Diabetes in Special Populations
People from minority groups, especially African Americans, Hispanic Americans, Pacific Islanders and Native Americans, are at increased risk for type 2 diabetes. Of the 3,234 participants in the DPP, 45% were from minority groups. The DPP also recruited from other groups known to be at high risk for type 2 diabetes, including individuals 60 years and older, women with a history of gestational diabetes, and people with first-degree relatives with type 2 diabetes (NIDDK, 2001).
"Lifestyle intervention worked as well in men and women and in all the ethnic groups," Nathan told GT. "It also worked well in people age 60 and older, who have a nearly 20% prevalence of diabetes.
"Metformin was also effective in men and women and in all the ethnic groups, but was relatively ineffective in older volunteers and in those who were less overweight," he continued.
The first study to look at the safety of metformin in children with type 2 diabetes revealed the antidiabetic agent to be "safe and effective for treatment of type 2 diabetes in pediatric patients" (Jones et al., 2002). The multicenter, double-blind, randomized study evaluated the safety and efficacy of metformin at doses of up to 1000 mg twice daily on 82 subjects, ages 10 years to 16 years. Improvement was found in the fasting plasma glucose levels of subjects of both genders and in all racial subgroups enrolled in the study (Jones et al., 2002).
Peters, who treats many patients with type 1 and type 2 diabetes, said primary care physicians should encourage their patients to exercise 30 minutes a day, five days a week, and eat meals high in fiber and low in saturated fat.
Practitioners should strive to keep their patient's HbA1c levels below 7, their blood pressure below 130/80 Hg mm, and monitor their patient's LDL level to make sure it does not go above 100. Patients should also be encouraged to see their eye doctor at least once a year.
References
ADA (2002), Implications of the United Kingdom Prospective Diabetes Study. Diabetes Care 25(suppl 1):S28-S32.
Diabetes Prevention Program Research Group (2002), Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 346(6):393-403.
Eriksson KF, Lindgärde F (1991), Prevention of type 2 (non-insulin-dependent) diabetes mellitus by diet and physical exercise. The 6-year Malmö feasibility study. Diabetologia 34(12):891-898.
Goldberg RB, Capuzzi D (2001), Lipid disorders in type 1 and type 2 diabetes. Clin Lab Med 21(1):147-172.
Hu FB, Manson JE, Stampfer MJ et al. (2001), Diet, lifestyle, and the risk of type 2 diabetes mellitus in women. N Engl J Med 345(11):790-797.
Jones KL, Arslanian S, Peterokova VA et al. (2002), Effect of metformin in pediatric patients with type 2 diabetes. Diabetes Care 25(1):89-94.
NIDDK (2001), Diet and exercise dramatically delay type 2 diabetes: diabetes medication metformin also effective. Available at: http://www.niddk.nih.gov/welcome.releases/8_8_01.htm. Accessed March 15, 2002.
Pan XR, Li GW, Hu YH et al. (1997), Effects of diet and exercise in preventing NIDDM in people with impaired glucose tolerance. The Da Qing IGT and Diabetes Study. Diabetes Care 20(4):537-544.
Tataranni PA, Bogardus C (2001), Changing habits to delay diabetes. N Engl J Med 344(18):1390-1392 [editorial].
Tuomilehto J, Lindström J, Eriksson JG et al. (2001), Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. N Engl J Med 344(18):1343-1350 [see comment pp1390-1392].
Patients Unaware of Link Between Diabetes and Risk of Cardiovascular Diseases
Diabetes is the sixth leading cause of death in the United States. Over 16 million people in the United States have diabetes and, although 11.1 million have been diagnosed, 5.9 million people are not aware they have it. Alarmingly, a recent survey conducted by the American Diabetes Association (ADA) and the American College of Cardiology (ACC) found that 68% of the 2,008 patients they surveyed were not aware of the link between diabetes and the risk of cardiovascular disease. The number of people with diabetes in the United States has risen almost 50% in the past decade, and nearly two-thirds of people with diabetes die of myocardial infarction or stroke. Adults with diabetes have heart disease death rates two to four times higher than adults without diabetes. Also, the risk for stroke is two to four times higher among people with diabetes.
"Many patients with diabetes are living with a very palpable risk for cardiovascular disease," said ACC president W. Bruce Fye, M.D., M.A., at a news conference. "And by focusing on that risk--as well as the risk of high cholesterol, hypertension, inactivity and smoking--we can have a dramatic impact on the health of the nation and on the health of individuals."
Sixty percent of those surveyed also did not feel that they were at high risk for high blood pressure or high cholesterol. According to ADA president Christopher Saudek, M.D., 60% of patients with diabetes have hypertension, and almost all have one or more cholesterol abnormalities including low levels of high-density lipoproteins or high levels of low-density lipoproteins. "There is a serious knowledge gap between the facts and the perceptions in diabetes," Saudek told the press.
In an effort to educate physicians and health care providers about the link between diabetes and cardiovascular disease, the ADA and ACC have sponsored the Make the Link! program. Both groups want to promote prevention of cardiovascular disease in people with diabetes by taking steps to reduce risk of cardiovascular disease.
The U.S. Health and Human Services' (HHS) National Diabetes Education Program has also developed a risk management campaign called ABCs of Diabetes (hemoglobin A1c test, blood pressure and cholesterol).
"This ADA survey reinforces the need to help people with diabetes understand their risk for heart disease and stroke--and what they can do to reduce those risks," said HHS secretary Tommy G. Thompson in a press release. "Not only controlling blood sugar, but also controlling blood pressure and cholesterol, is important to prevent heart disease and stroke in those who have diabetes."
In conjunction with the ABCs of Diabetes, the National Diabetes Education Program and the ADA are offering a free brochure for people with diabetes that includes information about managing their health and a wallet card to track their ABC numbers. These are available to the public through HHS at (800)438-5383 or <www.ndep.nih.gov> and through ADA at (800)DIABETES or <www.diabetes.org/makethelink>--RG
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