Launched in 1995, the DPP's main results were announced in 2001 and reported in 2002 [http://www.nih.gov/news/pr/feb2002/hhs-06.htm]: losing 5 to 7 percent of weight through diet and a consistent increase in physical activity (e.g., walking 5 days a week 30 minutes a day) reduced the onset of type 2 diabetes by 58 percent. Treatment with metformin lowered the chances of developing diabetes by 31 percent.
"To combat the dual epidemics of obesity and type 2 diabetes, Americans need to know about the proven benefits of losing some weight through calorie reduction and increased physical activity," said NIH Director Elias A. Zerhouni, M.D.
The DPP randomly assigned 3,234 overweight people with higher-than-normal blood glucose levels to one of three approaches to prevent type 2 diabetes: dietary changes and increased physical activity aimed at a 7-percent weight loss; treatment with the oral diabetes drug metformin; or placebo. The last two groups were also given standard medical advice about diet and weight loss. In the study, 660 women were randomly assigned to intensive lifestyle changes, 636 to metformin treatment, and 661 to placebo. Their average age was 50 years old, with an average body mass index of 35 (e.g., a 5' 4" woman weighing 204 pounds).
Women who implemented intensive lifestyle changes and lost 5 to 7 percent of their weight had fewer episodes of weekly incontinence compared to those in the metformin or placebo groups (38 percent vs. 48 percent vs. 46 percent, respectively.)
"Our findings reinforce the DPP's good news about the benefits of modest weight loss. A 200-pound woman who loses 10 to 15 pounds not only lowers the risk of developing type 2 diabetes but also improves bladder control," said lead author Jeanette S. Brown, M.D., of the University of California, San Francisco. "If you're a woman at risk for type 2 diabetes, preventing or delaying diabetes and improving bladder control are powerful reasons to make these lifestyle changes."
Weight loss was particularly effective in reducing episodes of stress incontinence--leakage of small amounts of urine during physical movement, such as coughing, sneezing, and exercising. Stress incontinence results, in large part, from a weakening of the pelvic floor muscles that support the bladder. Though researchers do not fully understand all the factors contributing to stress incontinence, it is linked to obesity, diabetes, and other conditions, such as pregnancy, which increase pressure on the pelvic floor. In the DPP participants, weight loss did not alleviate urge incontinence--leakage of urine at unexpected times. Urge incontinence is more closely linked to overactive nerves that control the bladder, sometimes triggering inappropriate contractions.
More than 13 million people in the United States, mostly middle-aged and older women, experience loss of bladder control. Overweight women and those with type 2 diabetes have a 50- to 70-percent increased risk of incontinence. In the National Health and Nutrition Examination Survey 2001-2002 sample, one out of three women with diabetes or prediabetic glucose levels reported weekly or more frequent episodes of UI.
Some studies have reported that increased physical activity worsens incontinence, but DPP participants randomly assigned to lifestyle changes, who typically chose walking as their physical activity, did not have increased problems with incontinence.
"Urinary incontinence is a costly, socially isolating condition that impairs quality of life and takes a psychological toll on many women. For women at risk for type 2 diabetes, losing a modest amount of weight is likely to alleviate incontinence, especially stress incontinence," said Leroy Nyberg, M.D., Ph.D., of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), which funded the study.
Nearly 21 million people in the United States--7 percent of the population--have diabetes, the most common cause of blindness, kidney failure, and amputations in adults and a major cause of heart disease and stroke. Type 2 diabetes accounts for up to 95 percent of all diabetes cases. The prevalence of type 2 diabetes has risen dramatically in the last 30 years, due mostly to the upsurge in obesity. In addition, about 40 percent of U.S. adults ages 40 to 74--41 million people--have prediabetes, which raises the risk of developing type 2 diabetes and cardiovascular disease.
The NIDDK funds a great deal of research to improve the treatment and prevention of diabetes and urologic disorders. These efforts include the Urinary Incontinence Treatment Network (http://www.uitn.net/) and the Specialized Center of Research on Lower Urinary Tract Dysfunction in women, a multidisciplinary translational research center at the University of California, San Francisco (www.ucsf.edu/scor). Recently, NIDDK's Central Repository [https://www.niddkrepository.org], which houses data collected in large clinical trials funded by the Institute, made data from the DPP available to researchers free of charge.
The NIDDK also sponsors "Let's Talk about Bladder Control for Women," a campaign to inform women about treatments for incontinence, from pelvic floor exercises to surgery. For more information, call 1-800-891-5388 or see www.niddk.nih.gov. The National Diabetes Education Program [www.ndep.nih.gov/], jointly sponsored by the NIH, the Centers for Disease Control and Prevention, and 200 partner organizations, is disseminating the DPP's good news through its education campaign, "Small Steps. Big Rewards. Prevent type 2 diabetes." [http://www.ndep.nih.gov/campaigns/SmallSteps/SmallSteps_index.htm]
The NIH--The Nation's Medical Research Agency --includes 27 Institutes and Centers and is a component of the U. S. Department of Health and Human Services. It is the primary Federal agency for conducting and supporting basic, clinical, and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, see http://www.nih.gov.
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