Can Diabetes Be Prevented?

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June 11, 2000 (San Antonio) -- Because the complications of diabetes are so devastating, finding ways to prevent it has the attention of scientists worldwide. The results so far are mixed: Lifestyle changes and medications may or may not help with type 2, or "adult-onset," diabetes, while injections of small amounts of insulin may prevent type 1, or "juvenile-onset," diabetes.

With type 2, which is linked to obesity, the devil is in the details: Which lifestyle changes can realistically be made -- and maintained -- in day-to-day life? A Finnish study presented here at the annual meeting of the American Diabetes Association (ADA) showed promising results, while British researchers were disappointed in the protective benefits of both lifestyle changes and oral medications.

The Finnish study involved people with a condition known as impaired glucose tolerance, which is considered a risk factor for type 2 diabetes. Of the 532 people in the study, those who received intensive support for changes in diet and exercise saw their risk of developing diabetes drop by 58%, says lead investigator Jaako Tuomilehto, MD.

"We were surprised that the effect of the intervention was so large," says Tuomilehto, a professor of medicine at the National Public Health Institute of the University of Helsinki. "We would like to know, however, if our findings are applicable outside of Finland."

The big challenge for people who lose weight is to keep it off. But the Finnish doctors tell WebMD their results were "better than most."

All of the patients studied were clinically obese. Those who got the intensive support and advice lost, on average, 10 pounds each during the first year of the trial. And they gained very little of that weight back in the following years, says Tuomilehto.

Even if people regain some weight, "a temporary loss may help delay progression by a few years," incoming ADA president Robert Sherwin, MD, tells WebMD. "This delay would in turn help forestall complications." Sherwin, also a professor of medicine at Yale University School of Medicine in New Haven, Conn., did not take part in the study.


The treated group received individualized advice and support for making lifestyle changes -- including how to lower total and saturated fat, how to increase fiber in their diets, and how to get, and stay, more physically active. The participants had monthly consultations the first year and less frequent but regular visits in the following 4 years. The comparison group didn't receive such hands-on advice but did get tips about diet and exercise at their annual check-ups.

But what if you're not so lucky as to get constant feedback and attention from a team of health care professionals? A British study presented at the ADA conference was designed with much less constant oversight and found that neither oral medication nor advice regarding a healthy lifestyle made much difference in preventing type 2 diabetes

In this study, 188 participants at high risk for type 2 diabetes were randomly chosen to receive either reinforced lifestyle advice or basic advice on healthy living. At the same time, the participants were assigned to groups that either received the diabetes medication gliclazide daily, a placebo "dummy" pill, or no tablets at all.

At the end of the six-year study, the participants receiving reinforced advice had lost somewhat more weight than the those getting basic advice, and they had less fat in their diets. However, the groups' rates of progression to diabetes were similar. The medication group, placebo group, and no-tablet group also had similar rates of progression.

The difference between the studies is probably because the Finnish study involved more structure and support, while the British study focused on supportive advice, Holman tells WebMD.

The problem with lifestyle changes is putting them into practice in a real-life situation, says Holman, professor of diabetic medicine at the University of Oxford in Cambridge, England. "The achievable ... changes in people leading routine lives are not large enough to reduce the risk of diabetes," he says. "Only greater changes will have this effect."

Insulin injections may prevent type 1 diabetes in people at risk of developing it, says Tihamor Orban, MD. He and colleagues at the Joslin Diabetes Center in Boston have followed 31 participants who have a parent or a brother or sister with type 1 diabetes as well as the blood antibodies for diabetes. They shared their findings at the ongoing ADA conference.


The investigators report that daily injections of a small amount of insulin under the skin helped slow down the onset of diabetes in the people they looked at; by the end of the study, 83% were free of disease. However, all of the people in the group that got no injections developed diabetes.

These findings give good evidence that such injections of insulin can either delay, or maybe even prevent, diabetes in people at risk of getting it, Orban, an instructor in medicine at Harvard Medical School.

"We don't know yet, though, if these people will require lifelong injections of insulin," he points out. Future studies may involve stopping the daily insulin shots to see if the treatment has lasting benefits.

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