(5 of 8)
The D.P.P. trial was halted a full year early "because the results were just so remarkable," says Dr. David Nathan, director of the Diabetes Center at Massachusetts General Hospital in Boston, who chaired the study. During the three years of the study, nearly 30% of the placebo group developed diabetes. For the metformin group the figure was 22%. The subjects who exercised moderately and lost weight had the lowest incidence of all--just 14%. (The first two groups were given diet and exercise information but did not lose as much weight as the last group.) The study is continuing to see if lifestyle changes can prevent diabetes for life or merely delay its occurrence. At the very least, the trial proves that the point of no return is not as early or as fixed as was once feared.
Diabetes researchers have been so impressed by the D.P.P. results that many would like to lower the thresholds that determine who is prediabetic. In January the American Diabetes Association plans to officially recommend that physicians consider treating anyone with a fasting glucose of 100 mg/dL or higher, down from 110 mg/dL or higher in the previous guidelines. "If your fasting blood sugar is below 100, your chances of getting diabetes are quite low," says Dr. Robert Rizza, an endocrinologist at the Mayo Clinic in Rochester, Minn., and a vice president of the American Diabetes Association. "But if your fasting glucose is over 100, you have a 10% to 15% chance of getting diabetes in the next seven years."
You don't have to convince Tom Marinello, 51, of Carson, Calif., that prediabetes should be taken seriously. After his father-in-law died of complications from diabetes, Marinello, unaware that he was at risk, enrolled in the Diabetes Prevention Program at the University of California, Los Angeles, hoping to help others with the disease. He was surprised to learn that he was prediabetic. By paying closer attention to what he eats and by making sure to walk nearly every day, Marinello dropped 28 lbs. from his 260-lb., 6ft. 1-in. frame, and his fasting-glucose level is down to 110 mg/dL. "I may still be at risk, but I'm not diabetic," Marinello says. "I'm kind of proud of that."
BEYOND APPLES AND PEARS
Is it possible to turn the clock back even further to find who is at greatest risk of developing prediabetes and lower their risk of future health problems? That turns out to be much more complicated.
Cardiologists have long known that if you carry extra weight around your waist, which they liken to being shaped like an apple, you are at greater risk of heart disease. The other configuration, being shaped like a pear, with excess weight around the hips, doesn't eliminate your risk but seems to lessen it. Over the years it has become clear that apple-shaped folks have a certain kind of metabolism: they are more likely to be resistant to insulin, have high amounts of triglycerides (one of the fatty molecules you don't want too much of in your blood) and have low levels of HDL (the "good" cholesterol). They also tend to have high blood pressure.