Rea Blakey: Diet, exercise can be powerful medicine

Rea Blakey

ATLANTA, Georgia, (CNN) -- A new study on diabetes joins others that consistently show daily exercise and a low-fat diet can be very beneficial, yet Americans on average seem to be less fit and more obese. CNN Health Correspondent Rea Blakey looks at the situation.

Q: Despite the years of attention given to fitness, why has the problem of obesity gotten worse and worse in America? Do Americans exercise less than they used to?

A. The Diabetes Prevention Program study from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) doesn't address the particulars as to why Americans have become more overweight and more obese during the last 30 years. But the fallout from all that extra tonnage is costing millions of healthcare dollars, and costing millions of Americans their health.

We know that 80 percent of Americans with Type 2 diabetes (adult onset) are overweight. And we also know that people with a body mass index (BMI) of 30 or greater have a five-fold greater risk of developing diabetes than people with a normal BMI of 25 or less. What the Diabetes Prevention Program (DPP) study shows us is, with just a little intervention -- 150 minutes of exercise weekly and a low-fat diet -- people who are predisposed to developing diabetes can stave off the disease, perhaps even prevent it.

Q: How is the average person to know that they are risk for type 2 diabetes?

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A. Overweight and obese people are obviously at risk. But so is anyone who has a first degree relative who has Type 2 diabetes. Women who developed diabetes during pregnancy (gestational diabetes) and many minorities are also at risk. In fact, African-Americans have a diabetes rate 60 percent higher than whites. Hispanic Americans have a diabetes rate 90 percent greater than whites. American Indians, Asian-Americans, and Pacific Islanders are all disproportionately affected by adult onset diabetes as compared to the general U.S. population. Researchers are still trying to figure this out.

The most sensitive, yet common, test used to confirm a Type 2 diabetes diagnosis is an oral glucose tolerance test (OGTT). It requires patients fast for 8 to 12 hours, then drink a glucose solution. (It's extremely sweet!!) Two hours later the patient's blood is measured. Normal levels of blood glucose are no higher than 140 mg/dl. Impaired glucose tolerance (often a precursor to diabetes) is in the range of 140 to 199. And a person is diabetic if the OGTT shows blood glucose is at 200 or more.

Q: Does the government have a plan to follow up on the study's findings?

A. Yes. The DPP studied whether medication or diet and exercise could prevent or delay the onset of Type 2 diabetes in people with impaired glucose tolerance. The results show diet and exercise can make a remarkable difference in holding off the disease -- 58 percent reduced risk, at least for the three years the subjects were studied. Researchers don't know if diabetes can be prevented long term.

Dr. David Nathan of Massachusetts General Hospital, the chairperson of the study, says, "We hope to follow the DPP population to learn how long the interventions are effective."

Researchers are still analyzing the data and performing more studies to determine whether the lifestyle interventions that are so effective in decreasing diabetes risk also affect the development of arteriosclerosis, which causes cardiovascular disease, or even cardiovascular disease itself.

Q: How might the pharmaceutical industry react to this report?

A. The popular diabetes drug Glucophage (chemical name: metformin) was also tested for its preventative effects. People taking Glucophage in the study reduced their diabetes risk by 31 percent. But people employing diet and exercise had better risk reduction rates, up to 71 percent among participants age 60 and older. The study shows Glucophage worked best in study volunteers who were the most overweight. As for the new formulation of metformin, Glucophage XR, it was not used in this study. Overall, pharmaceutical companies have got to sit up and take notice of the fact that diet and exercise are, in this case, pretty powerful!

Q: Does the study add credence to the notion that Americans think there is a medicinal fix for just about any medical problem? Should they scrap the pills and do 50 pushups?

A. Obviously, medications have their role in our society. But the Diabetes Prevention Program shows 50 pushups, water aerobics, or just walking for 150 minutes a week -- combined with a diet of no more than 25 percent of calories from fat -- may be just what many of us need to keep disease at bay.