The study, published in The Lancet, found a 34 percent reduction in new diabetes cases compared to a placebo in those who lost some weight and took part in physical activity. Also, diabetes incidence was reduced by 18 percent in those taking the diabetes drug metformin.

"The fact that we've continued to delay and possibly even prevent diabetes in people at very high risk for developing the disease is certainly a positive finding." study leader Dr. Jill Crandall of Albert Einstein College of Medicine of Yeshiva University in New York said in a statement.

The study is a long-term follow-up involving 88 percent of those in the Diabetes Prevention Program -- a large randomized trial in 2001 involving 3,234 overweight or obese adults at high risk for diabetes. The original study found modest weight loss combined with increased physical activity reduced the rate of developing type 2 diabetes by 58 percent compared to a placebo and an oral diabetes drug -- metformin -- reduced the rate by 31 percent.

The sustained lifestyle changes had multiple benefits -- including improved cardiovascular function -- especially pronounced among older people. Those age 60 and older lowered their rate of developing type 2 diabetes in the next 10 years by about half.