Preventing Diabetes

JIM LEHRER:

Diabetes, a common and deadly disease. Early results of a study on its prevention went so well, researchers stopped their clinical trial a year early and announced their findings today. Margaret Warner takes a closer look at those results.

MARGARET WARNER:

The study, sponsored by the National Institutes of Health, found diet and exercise can dramatically cut one's risk of getting diabetes. That's good news for the ten million Americans who are at high risk for the disease; another 16 million already have it. The study focused on type-II diabetes. People with it have lost their ability to process insulin, the hormone needed to convert blood sugar into energy.

The doctor who headed the study joins us now to explain its findings. Dr. David Nathan is the director of the Diabetes Center at Massachusetts General Hospital in Boston and a professor of medicine at Harvard Medical School. Welcome, Dr. Nathan. First, a little more about diabetes. Who gets it and how serious is it?

DR. DAVID NATHAN:

Well, diabetes is a chronic disorder that affects currently more than 16 million Americans. In particular it affects people who are overweight, people especially as they get older, and it also affects specific minority groups, African-Americans, Hispanic Americans, Asian Americans and Pacific Islanders and American Indians in particular get it at rates one and a half to almost eight times higher than the Caucasian population.

MARGARET WARNER:

And how much would you say it costs the health care system a year?

DR. DAVID NATHAN:

Well, the estimate is that it costs the health system $100 billion a year, that's not million, billion dollars per year.

MARGARET WARNER:

That's just to treat it?

DR. DAVID NATHAN:

Just to treat it.

MARGARET WARNER:

And when you say that minority populations are at greater risk, is this because of socioeconomic or lifestyle reasons, or is there a genetic component?

DR. DAVID NATHAN:

Well, there is certainly a genetic component. We know that Type II diabetes is inherited to some extent, we don't know the genes yet that cause it, but we know it's inherited.

MARGARET WARNER:

All right. Now tell us about the study. Who did you enroll in the study, how long did it go on?

DR. DAVID NATHAN:

Well, the idea behind the study was that diabetes is occurring at this epidemic rate, 800,000 new cases per year. It's clear that we can't keep up with those people. They are developing chronic complications over time, including loss of vision, kidney failure, heart attacks, amputations. So we decided to look at whether we could prevent the disease from occurring in the first place.

We looked at populations at particularly high risk and identified those who are at high risk with a glucose tolerance test, the test where people drink a sweet, syrupy-like liquid and the blood sugar is checked before they drink it and two hours afterwards. If their blood sugars are somewhat elevated but not high enough to be diabetic, then they are said to have impaired glucose tolerance. And that is the group that we selected. We also looked particularly in those communities that I mentioned before, and 45 percent of our study population was from the minority community.

MARGARET WARNER:

All right. Now, you put them on two or really three different regimens?

DR. DAVID NATHAN:

Right. We took those individuals who qualified for the study and we treated them either randomly assigned them, flipped them a coin, by chance, to either the medication Metformin, which is a drug that has been commonly used to treat diabetes in the past, a placebo pill, not the real thing, or to an intensive lifestyle intervention. The lifestyle intervention was designed to achieve a weight loss of 7 percent , at least 7 percent , and to increase their activity level to 150 minutes per week.

MARGARET WARNER:

What did you find?

DR. DAVID NATHAN:

Well, what we found was very gratifying. Both the Metformin and the lifestyle intervention were well accepted, they were safe, and the volunteers did what they were asked to do. So that the lifestyle intervention group increased their activity by an order of about 200 minutes, 220 minutes a week.

MARGARET WARNER:

Actually more than you asked.

DR. DAVID NATHAN:

Actually more than we asked — about 32 minutes a day, for example, over seven days a week. And they were able to decrease their weight at one year by 7 percent , which is approximately 15 pounds, 1–5, fifteen pounds, by three years they had lost a little bit of ground, it was 5 percent and 10 pounds. The Metformin group was able to take the medication, which was not absolutely clear when we started. This is after all for prevention. The results of those therapies were outstanding, we think; the lifestyle reduced the development of diabetes by 58 percent . And the Metformin reduced it by 31 percent — so really quite a large reduction for each.

MARGARET WARNER:

Now when you say you reduce the risk, in these people who had already been found to be at high risk, that is they didn't contract the disease, did you just you think delay the onset or did you prevent it? In other words, if they took the glucose tolerance test, had you actually reversed their glucose intolerance, or were they still sort of an accident waiting to happen, ready to blossom at any moment, just hadn't yet?

DR. DAVID NATHAN:

Obviously, we only studied them over an average of three years, the most was five years approximately. But the average was three years. So we can only say that we delayed it for three years or prevented it for three years. However, when we looked at other measures of blood sugar control, for example whether the blood sugar could be prevented from going even higher, let's say fastings greater than in 40, it appeared that we had also decreased that. And when we looked at whether these people still had their impaired glucose tolerance, lifestyle intervention, for example, decreased that by 35 percent . 35 percent were now having normal glucose tolerance.

MARGARET WARNER:

Now when you say, we heard Tommy Thompson — Secretary Thompson say it too, just 30 minutes a day, five times a week, moderate exercise, how moderate was this, aerobic exercise, just a good walk?

DR. DAVID NATHAN:

Let me point out that the lifestyle modification was really a modification of not just activity levels, it wasn't even exercise – just activity levels — but also included very importantly the weight loss — and absolutely clear that we need both components to have it work. The recommendation for their activity was to engage in activity, usually 30 minutes a night for at least five nights a week, and many of them did more, which was noted to be of moderate intensity – and that really is equivalent to brisk walking.

So we didn't ask them to become in Olympic swimmers, they didn't have to engage in hurdles. They didn't have to even sweat out the oldies — all they needed to do was increase their activity level by approximately 150 minute a week.

MARGARET WARNER:

Now, this sounds like really rather common sense advice. What's really new here?

DR. DAVID NATHAN:

It is, we've been hearing for years that diet is good for you, if you're overweight try to lose weight. What we've demonstrated here for the first time really in the U.S. population is that first they can do it. With all of the talk about whether people should be losing weight or not, this is the first study to demonstrate in a diverse population, these were people from all over the country, rural areas, urban areas, North, South, East, West, that people who volunteered for this study could accomplish the change in lifestyle that we asked them to and that they could take the Metformin to a high level. That's the first thing.

The second thing is that it's not a question of whether it will help them. We now have definitive evidence that it will work, it works across men and women, it works in all the ethnic and racial groups we studied. So it's not a question of guess work, we do have conclusive evidence that this will decrease the development of diabetes.

MARGARET WARNER:

So what do you recommend should be done with these results? For instance, if you're in any of those high-risk groups and you're overweight, should you immediately adopt this program, should you have a screening for glucose tolerance?

DR. DAVID NATHAN:

It's always good to refer those decisions to the patient's physicians, obviously. There are a number of groups that are meeting now: the American Diabetes Association, the National Diabetes Education Program, which will have a look at our data and decide how best to translate it. I feel it a little premature for me — we did the research.

We've demonstrated what can happen if this is applied. It's a little premature to say we should screen everyone or just this fraction of the population. But clearly there are it least ten million people out in the U.S. who look just like our individuals who volunteered for the study. They developed diabetes at a rate of 11 percent a year with the placebo. When we treated them, we reduced that dramatically, down to 7.8 percent per year on the Metformin and 4.8 percent per year in the lifestyle intervention. If we can apply those same interventions, we think we can get the same kind of results.

MARGARET WARNER:

As you know, lifestyle changes are the hardest thing to get people to do. How do you get the message out?

DR. DAVID NATHAN:

Well, we've been trying to get the message out here and in other places. I think we were going to get the message out as quickly as we can and hopefully, again, this was not a dramatic change, they didn't have to lose 50 pounds, it was 15. And I think that most of the American population can probably do that.

MARGARET WARNER:

All right, Dr. Nathan, thanks very much.

DR. DAVID NATHAN:

Thanks for having me.