THURSDAY, May 22 (HealthDay News) -- Diet and exercise programs for people at high risk for developing diabetes, when followed for six years, can actually delay the development of diabetes for 14 years after the programs end, a new report finds.

The report is published in the May 24 special diabetes issue of The Lancet.

In another study in the same journal issue, Chinese researchers found that intensive therapy with insulin in patients with newly diagnosed type 2 diabetes can help restore the cells in the body that produce insulin, and thereby restore blood sugar balance.

"Early intensive insulin therapy in patients with newly diagnosed type 2 diabetes has favorable outcomes on recovery and maintenance of B-cell function and prolonged glycemic remission compared with treatment with oral hypoglycemic agents," the researchers concluded.

In terms of the lifestyle study, a series of trials around the world have shown lifestyle changes in diet and exercise can reduce cases of diabetes in people with high blood sugar levels. However, whether these gains remain over an extended period isn't clear, researchers said.

"When you do lifestyle interventions in communities, it seems to have a durability beyond the life of the intervention itself, which is very encouraging," said co-author Edward Gregg, branch chief of the Epidemiology and Statistical Branch in the Division of Diabetes Translation at the U.S. Centers for Disease Control and Prevention.

In the trial, called the China Da Qing Diabetes Prevention Outcome Study, 577 adults with high blood sugar levels, at risk for developing diabetes, from 33 clinics in China, were randomly assigned to one of three lifestyle intervention groups. One group relied on diet, a second group on exercise and a third on a combination of diet and exercise. In addition, there was a group that did not participate in any diet or exercise program.

People were counseled to reduce the amount of food they ate and to cut down on sugar and alcohol, Gregg said. "People were encouraged to eat more vegetables and increase their levels of physical activity," he added.

The study began in 1986, and these groups continued their diet and/or exercise programs until 1992. In 2006, the people in the study were seen again to determine the long-term effect of diet and exercise.

Gregg's team found lifestyle interventions reduced the incidence of diabetes by 51 percent over the six years of the program.

Moreover, over the whole 20-year period, the incidence of diabetes was reduced by 43 percent in those people who had been in diet and exercise programs.

On average, the incidence of newly diagnosed diabetes was 7 percent for people who had participated in diet and exercise programs, compared with 11 percent for people who hadn't, the researchers reported.

By the 20th year, 80 percent of those who had participated in a diet and exercise program had developed diabetes, compared with 93 percent of the people who did not participate in such a program. People who had been in a diet and exercise program, spent 3.6 fewer years with diabetes than people who hadn't, Gregg's team found.

Gregg believes that similar programs could be effective in the United States. "Interventions used in this study are similar to interventions that have been used in the United States and do work," he said.

One expert says that despite these impressive results, the study does have a couple of important limitations.

"The majority of study participants in both intervention and control groups went on to develop diabetes eventually," said Dr. David Katz, director of the Prevention Research Center at Yale University School of Medicine. "Moreover, the study is unable to prove that the intervention conferred a survival benefit."

Another limitation is how these results from lifestyle changes can be translated into the real world, Katz said.

"Despite these limitations and the challenges that lie ahead, the finding that we can teach people to eat well and be active, and thereby provide them meaningful defense against diabetes that lasts for decades, is of extraordinary significance," Katz said.

In a third study, Finnish researchers found that incidence of type 1 diabetes has more than doubled among Finnish children in the past 25 years. The incidence of type 1 diabetes rose from 31.4 percent per 100,000 in 1980 to 64.2 percent per 100,000 in 2005.

The increase is expected to continue. This dramatic increase in type 1 diabetes appears to be a combination of genetic and lifestyle factors, the researchers say. For example, obesity among Finnish children has risen from 9.5 percent in the mid-1980s to 20 percent currently.

More information

For more about diabetes, visit the National Institute of Diabetes and Digestive and Kidney Diseases.

SOURCES: Edward Gregg, Ph.D., branch chief, Epidemiology and Statistical Brunch, Division of Diabetes Translation, U.S. Centers for Disease Control and Prevention, Atlanta; David Katz, M.D., M.P.H., director, Prevention Research Center, Yale University School of Medicine, New Haven, Conn.; May 24, 2008, The Lancet

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