over a long time period with a median followup of 11 years. More than 60 research papers have published findings from this program.
Behavioral Studies: A meta-analysis reviewing the efficacy of a behavioral intervention offers encouragement regarding the efficacy of exercise as a means of reducing glycosylated hemoglobin (HbA1c). Twelve aerobic and two resistance training studies found postintervention HbA1c to be “lower in the exercise groups compared with the control groups,” a difference that “should decrease the risk of diabetic complications” (Boule, Haddad, and Kenny, 2001).
The Diabetes Prevention Program (Diabetes Prevention Program Research Group, 2002) found that both lifestyle changes and drug treatments were effective in reducing the incidence of Type 2 diabetes. In this study, 2,324 nonaffected individuals who had elevated glucose concentrations but did not have diabetes were randomly assigned to one of three experimental conditions: lifestyle modification (diet and exercise), metformin administration twice daily, and placebo. The baseline characteristics of the study population included both genders; several ethnic groups (white, African-American, Hispanic, Native American/Alaskan Native, and Asian American/Pacific Islander); and variations in age, weight, family history, body-mass index, leisure physical activity, and blood glucose levels. The average followup was 2.8 years after the beginning of the trials. Although some disparities in occurrence of diabetes were found across ethnic groups, lifestyle changes provided the best outcome for all groups. Overall, lifestyle interventions reduced the incidence of diabetes by 58 percent relative to the placebo, while metformin reduced the incidence by 31 percent. Asians had the lowest incidence rate when following the lifestyle intervention, and African-Americans had the lowest incidence rate when administering metformin. Approximately half of the participants in the lifestyle treatment group met the weight loss goal of 7 percent, and three-quarters met the exercise goal of 150 minutes per week (at 6 months); at the 2.8-year