Lifestyle changes are the best way to stave off development of Type 2 diabetes, according to a 10-year followup of an innovative trial to prevent the disease in high-risk groups. The results are important because diabetes is a rapidly spreading epidemic in the United States. About 24 million Americans -- 1 in every 9 -- have diabetes, the vast majority of them Type 2, which develops during adulthood. An additional 57 million people have blood glucose levels that are higher than normal but that are not yet in the diabetic range, and it is this group that could benefit the most from interventions.
The original Diabetes Prevention Program trial involved 3,234 overweight or obese men and women, most of them from ethnic groups with an above-normal risk for diabetes. They were divided into three groups: one received intensive training on altering their lifestyle, the second received the diabetes medication metformin, and the third received a placebo. The lifestyle intervention involved reducing the amount of fat in their diet, exercising daily and losing 5% to 7% of their body weight. On average, those in this group exercised about 30 minutes per day and lost about 15 pounds, although they subsequently regained 10 pounds. Those in the metformin group lost 5 pounds, and those in the placebo group lost less than 2.
The study was halted prematurely in 2001 when it became clear that lifestyle intervention was most effective. Those in the lifestyle arm of the trial reduced their risk of diabetes by 58% compared with the placebo group, and those in the metformin group reduced risk by 31%.
The original group was offered the chance to participate in followup studies and 1,766 did, roughly a third from each of the trial arms. All were given training in lifestyle changes.
The study team, led by Dr. David M. Nathan of Massachusetts General Hospital, reported on the 10-year results this week in the journal Lancet. In the 10 years, participants in the original lifestyle-change group delayed the onset of diabetes by an average of four years compared with the placebo group, and those in the metformin group delayed it by an average of two years. "The benefits of intensive lifestyle changes were especially pronounced in the elderly," Nathan said. "People age 60 and older lowered their rate of developing diabetes in the next 10 years by about half."
About 5% to 6% of those in the lifestyle intervention group developed diabetes every year during the initial trial, a rate that remained constant over the follow-up period. About 8% of those in the metformin group and 11% of those in the placebo group developed diabetes each year during the original trial. Over the rest of the period, however -- apparently because of the added lifestyle training -- the latter two groups reduced their annual rate to the same range as those in the original lifestyle group.
In an editorial accompanying the report, Dr. Anoop Misra of Fortis Hospitals in New Delhi wrote that, "Prevention of diabetes is a long and winding road. There seems to be no shortcut, and a persistent and prolonged lifestyle intervention seems to be the most effective mode to travel on it."
-- Thomas H. Maugh II
Photo: Walking was the most common form of exercise in the lifestyle-change group. Credit: Robert Lachman/ Los Angeles Times