Exercise, Diet, Metformin Can Keep Diabetes at Bay for 10 Years

Nov. 1, 2009— -- Diet, exercise and, to a lesser extent, an inexpensive drug can help keep Type 2 diabetes at bay for up to 10 years, researchers said.

In a new study, individuals at risk of type 2 diabetes significantly reduced their chances of developing the condition by taking the diabetes drug metformin and adhering to a diet-and-exercise program, according to Dr. William C. Knowler and colleagues on the government's Diabetes Prevention Program Research Group.

Writing online in The Lancet, the researchers said people initially assigned to diet and physical activity modifications showed a 34 percent reduction in later diagnosis of type 2 diabetes during follow-up, compared to a group that took a placebo pill.

Another group assigned to metformin treatment were at 18 percent less risk for type 2 diabetes compared with the placebo group. Metformin is a popular oral drug often used as a first-line treatment for incipient Type 2 diabetes.

"Prevention or delay of diabetes with lifestyle intervention or metformin can persist for at least 10 years," Knowler and colleagues wrote.

Beginning in 1996, the original study assigned more than 3,800 people showing impaired glucose tolerance, but not full-blown diabetes, to participate in an intensive diet-and-exercise program, to receive metformin, or to receive placebo.

By 2001, the results showed a 58 percent reduction in diabetes diagnoses in the diet-and-exercise group and a 31 percent reduction in the metformin group.

In addition to diabetes incidence, the researchers also tracked body weight of the subjects in the study. What they found was that those taking the metformin lost about 2 kg (4.4 pounds) in the first year of the trial, which was maintained during the rest of the randomized phase and throughout the follow-up.

During the randomized phase, participants in the diet-and-exercise arm lost a mean of almost 7 kg (15.4 pounds) in the first year, but regained weight in the next two years, for a net loss at year three of about 4 kg (8.8 pounds). By year five, the net loss had shrunk to 2 kg (4.4 pounds), which continued to the end of follow-up.

Little change was seen in placebo patients' weight throughout the 10-year study.

However, when looking only at participants 60 and older at randomization, those assigned to the diet-and-exercise program steadily regained weight throughout the study after an initial 7-kg (15.4-pound) loss, whereas those in the metformin and placebo groups both lost weight after the randomized trial ended.

By year 10, weight loss in this older population relative to baseline was nearly identical for all three treatment groups, at about 4 kg (8.8 pounds).

Limitations of the study included the modifications to initial treatments during the follow-up study and lack of data on the significant proportion of initial participants who were lost to follow-up.

Despite those caveats, an accompanying commentary by Dr. Anoop Misra of Fortis Hospitals in New Delhi, India, said the randomized and follow-up studies together prove that "an intensive lifestyle intervention is effective over 10 years, and remains the best bet for prevention of diabetes."

But Misra added that the study left other important questions unanswered, such as the mechanism underlying metformin's benefit.

"It is not clear whether metformin is masking, suppressing, or just delaying diabetes," he wrote.

He also wondered whether the modest benefit in the metformin group was worth the drug's cost.

"Prevention of diabetes is a long and winding road," Misra wrote. "There seems to be no shortcut, and a persistent and prolonged intensive lifestyle intervention seems to be the most effective mode to travel on it."