WASHINGTON — One-year data from a large, federally funded clinical trial have shown that intensive lifestyle intervention can produce significant weight loss and reduce cardiovascular risk factors among patients with type 2 diabetes, Dr. F. Xavier Pi-Sunyer reported at the annual scientific sessions of the American Diabetes Association.
The Look AHEAD (Action for Health in Diabetes) study is an ongoing 16-center randomized clinical trial designed to determine whether intensive lifestyle modification—including both decreased caloric intake and increased physical activity—can reduce the rates of both fatal and nonfatal myocardial infarctions and strokes in overweight volunteers with type 2 diabetes over a planned follow-up of 11.5 years, compared with traditional medical care.
The trial was funded primarily by the National Institutes of Health; other major donors include Federal Express, Health Management Resources, Johnson & Johnson, Lifescan Inc., Optifast-Novartis Nutrition, Roche Pharmaceuticals, Ross Products Division of Abbot Laboratories, and SlimFast Foods Company.
The study includes 5,145 patients with type 2 diabetes with a mean age of 59 and mean body mass index of 36 kg/m
The intensive lifestyle intervention (ILI), to which 2,570 patients were randomized, consisted of an initial 6-month phase in which they attended three group sessions and one individual session per month, all conducted by trained diabetes educators and emphasizing nutrition and physical activity aiming at a personal weight loss goal of 10% from baseline.
During months 7 through 12, subjects attended two or three sessions per month, either individually or in a group. Those who had achieved the first goal were aiming to maintain their weights, while those who hadn't continued to aim for the 10% loss.
Calorie recommendations were calculated based on baseline and goal weights, initially set at 1,200–1,500 kcal/day for those weighing 250 pounds or less at baseline and 1,500–1,800 kcal/day for those weighing more than 250 pounds. Participants could choose a regimen that included liquid meal replacements. Exercise was gradually increased to at least 25 minutes/day. Most participants walked, aiming for 10,000 daily steps, said Dr. Pi-Sunyer, director of the Obesity Research Center, St. Luke's-Roosevelt Hospital Center, New York.
The 2,575 control patients received diabetes support and education (DSE) consisting of three to four group meetings per year in which diet, exercise, and social support were discussed but no intervention was actually delivered, he said.
Of the 97% of study subjects who attended the 1-year exam, the ILI group had lost a mean of 8.3% of their body weight, compared with 0.4% in the controls, a highly significant difference. The average weight loss was about 18 pounds. The ILI group continued to lose weight for about the first 8 months of the study, after which their weight tended to plateau but did not rebound.
On average, the men lost about 3–4 pounds more than the women did. By race, whites lost a mean of 10% of their baseline body weight, compared with about 6.5% for Hispanics and African Americans and 6% among Native Americans. The 385 insulin users in the group lost a mean of 7% of their baseline body weight, and the 1,464 on oral antidiabetes medications lost 8%, whereas the 326 not taking any medications lost the most, with a mean of 9%.
Fitness, as measured by treadmill testing, improved by 16% in the ILI group and 11% in the controls, after adjustment for weight loss. Fitness improved significantly across all body mass indexes and in both genders and all the ethnic/minority groups. Changes in fitness were highly correlated with changes in activity level and in body weight, Dr. Pi-Sunyer noted.
Hemoglobin A1c levels dropped from 7.25% at baseline to 6.6% at 1 year in the ILI group, a highly significant difference. In contrast, the drop from 7.3% to 7.15% in the DSE group was not significant.
Similarly, fasting glucose dropped by a mean of 21.5 mg/dL with ILI, compared with just 7.2 mg/dL in the DSE group. The improved hemoglobin A1c occurred despite a greater reduction in glucose-lowering medications in the ILI group, he noted.
Systolic blood pressure dropped by 6.8 mm Hg in the ILI group vs. 2.8 mm Hg with DSE, and diastolic by 3.0 mm Hg vs. 1.8 mm Hg. Again, the reduction was significant only for ILI. Although LDL cholesterol levels didn't change significantly in either group, HDL cholesterol rose to a greater degree with ILI (3.4 vs. 1.4 mg/dL). Triglycerides dropped by 30.3 mg/dL with ILI, compared with just 14.6 mg/dL for DSE.
At 1 year, the ILI group was taking an average of 2.7 medications for glucose, blood pressure, and/or lipid lowering, compared with 3.2 for the DSE group, Dr. Pi-Sunyer reported.