Results from the Diabetes Prevention Program Outcomes Study (DPPOS), which included 2,766 of the DPP participants, shows that the diet and exercise group not only cut their risk of developing diabetes by 34 percent over a 10-year period, but also sustained a moderate weight loss and had lower blood pressure and triglyceride levels. People over 60 got even more dramatic results, cutting their risk of diabetes during the study period by about half. The group initially assigned metformin and later added in the lifestyle program had an 18 percent lower risk of developing diabetes. “Interventions that result in weight loss lower the risk of diabetes, and that lower risk appears to persist for a long period of time,” said study author Dr. William C. Knowler of the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.

Knowler acknowledges that losing weight is a difficult task and can’t be accomplished simply by telling people to slim down. “To make things like this happen on a large scale, we have to do more than simply tell people to lose weight,” he said, adding that people need access to weight loss clinics that can teach them about diet and exercise.

“When you consider the devastating medical complications that go with type 2 diabetes, these are very significant findings,” said Dr. Ronald Goldberg, principal investigator of the University of Miami Miller School of Medicine arm of the study. “It demonstrates that lifestyle changes can last as long as 10 years in preventing or slowing diabetes in people who are at risk.” Dr. Griffin Rodgers, director of the National Institute of Diabetes and Digestive and Kidney Diseases, agrees, saying that “millions of people could delay diabetes for years and possibly prevent the disease altogether if they lost a modest amount of weight through diet and increased physical activity.”

Dr. Anoop Misra, director of the department of diabetes and metabolic diseases at Fortis Hospitals in New Delhi, India, and author of an accompanying journal editorial, says the study shows that lifestyle intervention is “the best bet” for effectively preventing diabetes. “Diet and exercise remain the most important modalities to prevent diabetes, and any drugs are less important.”

Misra says all nations should take steps to help curb the diabetes epidemic, such as regulating the advertisement and sale of “energy-dense junk food to children” and encouraging regular physical activity starting at an early age. “Spreading awareness about proper lifestyle and adverse consequences of obesity and diabetes should be at the top of health agenda of all nations.”

The results of the DPPOS study are published in the October 29 online edition of The Lancet.

Compared to their untreated counterparts, the women who received diabetes treatment were 60 percent as likely to develop high blood pressure during pregnancy or to develop preeclampsia, a life-threatening complication that can lead to maternal seizures and death, and 80 percent as likely to give birth by cesarean section. Babies born to the women in the treated group were half as likely to be overweight or abnormally large and to experience shoulder dystocia, a condition where the baby’s shoulder becomes lodged inside the mother’s body during delivery. “Whether to treat mild gestational diabetes has never been entirely clear,” said coauthor Catherine Y. Spong, chief of the Pregnancy and Perinatology Branch at the NICHD. “The study results show conclusively that both mothers and infants do better when gestational diabetes is controlled.”

In an editorial accompanying the study in The New England Journal of Medicine, Dr. David Sacks, a maternal-fetal medicine specialist at the Kaiser Foundation Hospital in Bellflower, California, said the results of the study combined with a 2005 Australian study that also found treating gestational diabetes reduced the rate of serious complications around the time of delivery “clearly support the treatment of gestational diabetes” but posed the question, “however, now that the value of treatment is established, whom do we treat?”

Boyd Metzger, professor of metabolism and nutrition at the Northwestern University Feinberg School of Medicine, suggests the answer to that question may be found when new international guidelines for diagnosing gestational diabetes are published. Metzger was the lead scientist for the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study, a six-year study that spanned nine countries and included about 25,000 women. HAPO found a continuous increase in complications as blood sugar levels rose, indicating that treatment would be beneficial at any point.

Dr. Miriam Greene, an obstetrician and gynecologist at NYU Langone Medical Center, says she has already been treating women with the mildest forms of gestational diabetes, and that it does make a difference. Clearly, “when women with mild gestational diabetes are treated well, there’s a decreased incidence of birth trauma,” she said.

Rates of gestational diabetes have been increasing as more women begin their pregnancy overweight. The condition affects from 1 to 14 percent of all U.S. pregnancies and is thought to occur because of hormone changes that interfere with the body’s ability to make and use all the insulin it needs, causing blood glucose levels to get too high. The good news is that gestational diabetes usually goes away after the baby is born. The bad news is that women who develop the condition may also get it again in subsequent pregnancies.