T Nation

Diabetes Prevention Program


This ( and the other 5 pages that go with it ) makes interesting reading:


I posted it here as its nutrition, hope the mods agree.


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It’s a long way across the color palette from the beiges, whites, and browns of glazed doughnuts, colas, ice cream, and Ding Dongs to the reds of apples, squash yellows, bright oranges, and purple grapes. And then there are the seemingly infinite shades of green—spinach, beans, zucchini, cabbage, romaine lettuce. When sixty-six-year-old Edelmira Arteaga opens her refrigerator door to show a visitor, she contemplates her lifestyle changes over the past decade and sums them up in these simple terms. “It’s the colors,” says the East Los Angeles resident, a Latina who emigrated from Mexico more than four decades ago. “Different colors. Everything is fresh. Everything healthy.”

Arteaga made those color-coded dietary changes as one of 3,234 participants in the Diabetes Prevention Program (DPP), a federally funded study that began in 1996 and ended in 2001. This landmark clinical trial proved that a diverse group of Americans—overweight, with impaired glucose tolerance, and at risk of developing full-blown diabetes—could successfully undertake interventions to delay the onset of diabetes or prevent it altogether. Arteaga and other study participants accomplished that by changing the colors of foodstuffs in their kitchens, eating a healthier diet, adding a modest amount of exercise to their daily routines, and shedding some pounds. In fact, by losing just 7 percent of body weight and exercising moderately (only two and a half hours a week), Arteaga and others reduced their risk of developing diabetes during the study period by a whopping 58 percent.

The results blew the lid off some longstanding assumptions when they were published in 2002. In effect, they showed that many of the fifty-seven million Americans at high risk for type 2 diabetes could be spared some, perhaps all, of the suffering from the disease. Rather than being consigned to a future of chronic illness, they could slow or conceivably halt the progression from prediabetes to diabetes. By contrast, if those prediabetic populations did nothing to change their behavior, they would in all likelihood develop type 2 diabetes within ten years; possibly go on to have heart attacks or strokes; potentially lose their limbs, eyesight, and kidney functioning; and probably die years before their time.

On the other hand, the DPP study showed that if every one of those fifty-seven million people with prediabetes were able to make the lifestyle changes that the study participants made, ten million would sharply lower their risk of developing type 2 diabetes. And the study results were surprising in other ways as well. The DPP showed that lifestyle interventions could be more effective prevention tools than taking medication—specifically, metformin, a drug used to control type 2 diabetes.

At the same time, the study underscored key lessons about prevention that have major implications for public health. Although measures to prevent disease can be effective, they’re often not easy, since they can involve changes in human behavior that are difficult for people to make. What’s more, optimal prevention interventions can be labor-intensive and costly over the near term, even as they lessen the likelihood of disease many years off. Contrary to popular belief, then, prevention might not actually save money. Nonetheless, prevention might also constitute a cost-effective investment that produces real returns over the long haul for the dollars spent up front in forestalling disease.[1]

Prevention initiatives like those tested in the Diabetes Prevention Program raise additional questions as well. Intensive, costly interventions to change behavior clearly work, but are there ways to execute similar strategies in less costly ways? What’s more, can these carefully planned and orchestrated interventions really be replicated outside of trial settings and prove useful in the real, messier, less organized world?

These questions take on added significance at a time when Congress and the incoming administration of President-elect Barack Obama contemplate major health reforms. Fostering a far greater emphasis on prevention is near the top of the list of many policymakers’ plans for remaking U.S. health care. For example, in a reform roadmap released in November 2008, Senate Finance Committee chairman Max Baucus, a Montana Democrat, advanced a number of new prevention and wellness initiatives. His “Call to Action” stated that prevention “must become a cornerstone of the health care system rather than an afterthought. …With a national culture of wellness, chronic disease and obesity will be better managed and, more importantly, reduced.”[2]


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Avoiding one of those chronic diseases—diabetes—led investigators at the National Institute of Diabetes and Digestive and Kidney Disorders (NIDDKD) to begin designing a prevention study in 1994. Clinicians knew that when patients with diabetes made a few key lifestyle changes, they could improve control over their condition. So it seemed reasonable to ask whether similar lifestyle changes or use of medication could prevent or delay the onset of diabetes in people at high risk for the disease.

The multicenter trial that resulted, the DPP, ultimately involved 3,234 nondiabetic participants from various racial and ethnic backgrounds. To qualify for the study, volunteers had to be age twenty five or older, with a body mass index (BMI) greater than or equal to 24 kg/m2 (22 for Asian Americans) and impaired glucose tolerance. They were randomly assigned into four separate trial “arms,” testing four different approaches against each other. The arm Arteaga was in underwent the lifestyle- change regime, complete with intensive motivational counseling. In a second arm, enrollees took 850 mg of metformin (Glucophage) twice daily; they also received information about diet and exercise, but they underwent no intensive counseling. A third group received placebo pills and basic diet and exercise information without intensive counseling. A fourth group received another diabetes drug, troglitazone (Rezulin). However, this arm of the study was discontinued after two years, when researchers discovered that the drug could cause serious liver damage and the drug was withdrawn from the market. The various arms of the trial were designed to determine whether the rate at which prediabetes converted to diabetes could be lowered.

In the lifestyle-change arm, Arteaga got the kind of attention that few like her in the real world routinely experience. In effect, she had an entire team of experts devoted to her wellbeing. Like others in this arm of the trial, she got an individual lifestyle coach to provide advice on eating and exercising. Most of these coaches were registered dietitians; the rest typically had a master’s degree in exercise physiology, behavioral psychology, or health education. Trial participants like Arteaga began the program with a sixteen-session curriculum, learning about nutrition, exercise, and behavioral self-management. They kept journals noting everything they ate and all of their daily physical activity. Their entries were monitored and discussed weekly with their coaches.

If these trial participants didn’t have a scale at home to weigh themselves, they were given one and asked to weigh themselves at least weekly. Their calorie goals were individually prepared and calculated to achieve a weekly weight loss of one to two pounds. They were taught what a calorie was, what a fat gram was, and how to read labels and keep track of what all of this information meant for their bodies and their overall health. After the sixteen-session program, they met with their coaches face-to-face at least every two months, and talked on the phone at least once between visits.

In some respects, the coaches and others in the trial became the federally funded equivalent of nagging relatives, determined to keep participants adherent to the trial interventions and deeply motivated. They sent reminders to the trial participants to show up for appointments or to attend exercise and nutrition classes. They made phone calls. Interpreters were on hand to translate from English to Spanish or Japanese or Chinese, all with sensitivity to cultural differences. When participants didn’t have telephones, the coaches knocked on doors. If no one answered, they left notices behind, carefully rendered in the appropriate language.

Participants also received an array of incentives that varied from one research center to another, but typically included running shoes, pedometers, digital scales, water bottles, umbrellas, aerobics tapes, cookbooks, and grocery store vouchers. The budget for incentives, which the study called a “toolbox of strategies,” was $100 per participant per year


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It is hard to overstate the impact all of these interventions had on Arteaga’s life. She once weighed 200 pounds and led a largely sedentary lifestyle. Now she weighs 160 pounds and walks for forty minutes, three times a week: past the baseball field, the children’s playground, and the recreation center; twenty minutes in the morning and another twenty minutes in the evening. At night, she’ll switch on the radio to listen to Latin American folk music, coaxing her husband to join her for ten minutes of dancing.

Meanwhile, Arteaga’s consumption of overall calories and fatty carbohydrates has fallen dramatically, she says. “I used to eat many tortillas— eight in the morning, and eight in the evening. Every day, sixteen tortillas. Now I eat only two, one in the morning and one in the evening.” Until she joined the study, she says, she had no idea how the sugars and fats that she loved were affecting her body’s ability to produce and use insulin. She learned to write down what she eats, to read nutrition labels. From a dietitian in the study, she learned an aphorism attributed to Socrates: You can either live to eat, or you can eat to live. “I want never to forget that,” Artega now says. So in her cupboards, the shelves that once held mostly canned and processed foods—refried beans, jelly, cookies, and chips—now store brown rice, dried beans, raisins, prunes, almonds, and reduced-sugar fruit spreads.

In the end, the results in both treatment arms were impressive, although nowhere more so than in the lifestyle group. The 58 percent risk reduction achieved by this group overall was only outdone by the oldest participants— those age sixty and older—who reduced their risk of developing diabetes by an astonishing 71 percent. Overall, just five of every hundred people in the lifestyle group developed diabetes every year of the study,while in the placebo group, eleven of every hundred went on to develop diabetes each year. People taking metformin also reduced their risk of developing diabetes, by 31 percent. Overall, 7.8 percent of the trial participants taking metformin developed diabetes each year, compared to 11 percent in the placebo group.

Yet all of these interventions were, to say the least, intensive—and expensive. When the study group’s statisticians analyzed the cost of both the lifestyle and the metformin interventions compared to the placebo arm of the DPP, they came up with an additional cost to the health system of $2,191 per participant over three years in the metformin group, and $2,269 per participant over three years in the lifestyle arm (these are the direct costs of the intervention, without counting any savings from not having to treat the cases of diabetes that the intervention prevented).[3] The authors noted, however, that the cost of the lifestyle intervention decreased annually over the three years and could be expected to continue to decrease further over time. And, they concluded, the costs were modest and “must be balanced against the savings related to averted disease.”

However, another group modeling the cost effectiveness of the DPP interventions found them to be of questionable value, unless the cost of the interventions could be reduced substantially.[4


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The emphasis on the costs or cost-effectiveness of this prevention initiative strikes a familiar chord in the prevention debate. One school of thought focused on evaluating prevention tends to view these interventions through a purely dollars and- cents, return-on-investment lens. Those who are more concerned about improving public health overall view the results of the DPP through that perspective: can any set of interventions actually achieve gains in public health? Sandy Garfield, senior adviser for the Biometry and Behavioral Research Program at the NIDDK (National Institutes of Health), which sponsored the DPP, is a case in point. “This was a test of principle,” Garfield says. “When those studies are positive, you take those outcomes and, through other researchers and institutions, you try to translate that to public health.” And that may indeed involve looking for ways to deliver those same effective interventions at the least possible cost.

That’s exactly what David Marrero, principal investigator at the Indiana University, Indianapolis, DPP site, set out to do in a pilot study of ninety-two participants at YMCAs in the Indianapolis area. Using the same DPP training materials, researchers made modifications designed to lower the costs but achieve the same results. Instead of master’s-level coaches, they used YMCA staff employees. Instead of one-on one coaching, they did education and training in groups. And they eliminated the costly freebies aimed at helping entice people to exercise, like giving them aerobics tapes and water bottles. In the end, “we got wildly good results” at a cost for a sixteen session training program of about $235 per participant, Marrero says. The prediabetes participants in the YMCA lifestyle program lost 6 percent of their body weight, compared to a 2 percent loss in a control group within six months, and they maintained the weight loss for a year.

The Indiana University pilot study also demonstrated the value of other modifications in the original trial design, such as offering a program that was more widely dispersed into local communities. “Offering a program in people’s communities has advantages,” Marrero says. “In the DPP, people had to come to us in downtown Indianapolis.” By contrast, in the YMCA program, people attended sessions close to home, near neighbors, and they “started working and bonding together.”

Richard Kahn, chief scientific and medical officer of the American Diabetes Association and a coauthor of the published DPP cost analysis, is among those who think that the original DPP interventions were too costly as designed to be replicable in the general population in a cost-effective way. “You’re not going to get a health care institution to pay for frequent visits to a dietitian, to pay for exercise equipment, to buy health club memberships, to cajole and badger,” he says. In addition, says Kahn, people in the trial “were very motivated, and very eager to do what was asked.We need solid evidence that this would work for the average sedentary, overweight American. We need research on how to implement it in a practical way.”


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In fact, another trial participant, Alvivon Hurd, 73, may be a better exemplar of how hard these lifestyle and other changes are to make in the real world. Hurd was a participant in the DPP trial and, by luck of the draw, ended up in the metformin arm of the study, rather than in the lifestyle arm, as she was hoping. “I didn’t want to take the drugs,” says Hurd. But she had relatives who had diabetes, including an aunt whose leg had to be amputated when complications of the disease led to loss of circulation. At Hurd’s local church, Boyle Heights Christian in Los Angeles, parishioners had been praying that one member, who lost a toe and then a foot to diabetes, would not also lose a leg. Hurd, who had polio as a child, deeply feared being unable to walk again. “This program socked it to me,” she says of the DPP. “I don’t want loss of limb.”

Like all participants in the metformin arm, Hurd got introductory information on the importance of diet and exercise to prevent diabetes. But she didn’t get the sixteen-week training program, the one-on-coaching, and the nagging reminders that the lifestyle group received. Since the DPP ended, she remains enrolled in the follow-up study, the Diabetes Prevention Program Outcomes Study (DPPOS), and for several years she has been going to scheduled exercise and nutrition classes— about once every three months. Even now, she remains more consistent with the morning dose of metformin than the evening dose. “Like last night, I came home at twelve o’clock,” she says. “I’m not thinking about a pill at midnight.”

Hurd has also learned the lessons of good diet and exercise more slowly than Arteaga did. Each time Hurd now has a clinic visit or a class, she renews her resolve to eat better and exercise more. For the past two months, she’s been rising with the sun,walking a half a block to a park within her housing complex, and, with her pedometer hooked to her jogging pants, walking around and around. “I know that 5,280 steps equals a mile,” she says. “So I walk for fifteen minutes and see how many steps I can do. Then I take a break. Then I do it again, fifteen more minutes. I do it early in the morning, it’s nice and cool, and I’m looking at God’s creation.”

But after more than a decade enrolled in the DPP, it’s still easier for her to rattle off the list of foods that she misses—hot dogs, salami, peanut butter and jelly, candy, cake, ice cream, cookies—than to name a few healthy foods she now likes. “My darling,” she says, offering a term of endearment to just about everyone she meets, “I am a junk eater. I love it. I love candy, doughnuts, tacos, burritos. I’m not one who sits down at the table and eats a main meal. Even when I was raising my son, we would lie there and look at TV and eat Ding Dongs. Oh my God,when I think of how we ate!” At 5 feet, 2 inches tall, Hurd weighed 187 pounds when she enrolled in the DPP in November 1997, and her weight graph shows a bumpy up-and down road to her present weight of 167. “After eleven years, I’ve only lost twenty pounds,” she says. “But without it, I might be 197 now.”

Since the main phase of the DPP trial ended in 2001, about four-fifths of the original enrollees have continued in a follow-up phase. They’re being evaluated to see if they maintain the good results achieved earlier, and to see if they suffer fewer long-term complications of diabetes, such as heart disease. The first results from the five-year follow-up study are now being tallied, and are scheduled to be published in early 2009.

Arteaga is one of those who’s still being followed in this continuation phase. At the end of the main phase of the trial in 2001, she was among the 38 percent of lifestyle participants who maintained a weight loss of at least 7 percent. Now, 11 years after enrolling in the study, she has fully incorporated the dietary and exercise changes into her routine. That underscores what many observers of the DPP now believe: that what the study proved no longer needs proving. “We demonstrated with great, great confidence the effect you get,” says David Nathan, chair of the DPPOS and director of the Diabetes Center at Massachusetts General Hospital. “We know very well that it works,” he says, adding that it’s time to scale up these interventions nationally


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Kahn agrees that the DPP supplied “proof of principle” that the interventions worked—but says it’s now time to demonstrate that “we can get the same results at much less cost.” He says that the study results should now trigger federal or state initiatives to create tax incentives or disincentives to either lose weight if overweight or not put on excess weight. Policies aimed at increasing the number of bike paths, sidewalks, and parks to encourage exercise are also warranted, Kahn says.

In the end, the lifestyle participants went through what amounts to a kind of graduate level education in how to change their lives. Nowadays, Arteaga sets out every Saturday morning on a weekly ritual: a trip to the local farmers’ market. Returning home, she unloads a half-dozen bags filled with foods of many colors. For lunch, she sits down to a big, fresh salad—no tortillas, por favor. When her favorite music comes on the radio, she grabs her husband’s arm and gets him to dance. She plans to keep doing that for many years to come.