Every kilogram of weight loss resulted in 16% reduction of diabetes risk.
Among participants in the intensive lifestyle intervention arm of the Diabetes Prevention Program, weight reduction had the strongest effect on reduction of diabetes risk compared with diet and physical activity.
“The Diabetes Prevention Program (DPP) reported a 58% reduction in the incidence of diabetes over almost three years in [participants] treated with an intensive lifestyle intervention compared with participants treated with placebo,” the investigators wrote in Diabetes Care.
To further understand the specific methods by which lifestyle intervention resulted in this lowered diabetes risk, Richard F. Hamman, MD, DrPH, chairman of the department of preventive medicine and Biometrics at the University of Colorado Health Sciences Center, and colleagues analyzed the relative contributions of changes in diet, physical activity and weight loss to the reduction in diabetes incidence.
The intensive lifestyle intervention arm of the DPP included 1,079 participants aged at least 25 years with a BMI of at least 24 (22 in Asian-Americans).
The goals of the intervention included a weight reduction of 7% from baseline, to achieve and/or maintain at least 150 minutes per week of moderate physical activity and to reduce dietary fat intake to 25% of calories.
During the mean follow-up period of 3.2 years, a total of 153 participants developed diabetes (five per 100 person-years). After one year, participants’ mean weight loss was 6.8 kg (7.2%); the weight loss among the 638 participants who completed a three-year assessment was 4.1 kg from baseline. “Both measures of leisure physical activity showed significant increases at each of the 3 years,” the investigators wrote. “Percent of calories from fat was reduced from 34.1% to 27.5% at year one.”
Using separate models adjusting for baseline factors, researchers found that weight loss and baseline weight were most strongly associated with lower diabetes incidence compared with lower energy or fat intake and increases in energy expenditure. They found hazard ratios of 0.81 per 10-kg-lower baseline weight (P<.0001) and 0.49 per 5-kg-weight loss (P<.0001). “On average, there was a 16% reduction in diabetes risk per kilogram weight loss.”
In multivariate analyses, weight loss was the dominant factor for reduction of diabetes risk (HR, 0.42 per 5 kg; P<.0001). The reduction in risk due to weight loss was similar across all race/ethnicity groups, for both sexes and for all ages.
Researchers also explored the impact of meeting specific goals. The risk for diabetes decreased as additional goals were met, and the lowest risk was found when participants met all three goals (HR 0.11; 95% CI, 0.05-0.24).
With regard to predictors of weight loss, lower baseline percent fat and a reduction in percent fat after one year were associated with short- and long-term weight loss. Researchers said that “increased physical activity became a stronger predictor of weight loss at each subsequent year.”
When contrasting participants in the 90th vs. the 10th percentiles of weight reduction, there was a 96% reduction in risk. “This suggests that [participants] who lose even more weight than the DPP average, and who meet physical activity and dietary fat goals, could
reduce their diabetes risk by more than 90%,” the investigators wrote. “Interventions to reduce the incidence of diabetes should aim at weight loss as the primary determinant of success.”
Hamman RF, Wing RR, Edelstein SL, et al. Effect of weight loss with lifestyle intervention on risk of diabetes. Diabetes Care. 2006;29:2102-2107.