The influence of age on the effects of lifestyle modification and metformin in prevention of diabetes.

BACKGROUND

The incidence of type 2 diabetes increases with age. It is unknown whether interventions to prevent diabetes are as effective in elderly persons as in younger adults.

METHODS

The Diabetes Prevention Program (DPP) demonstrated that an intensive lifestyle intervention (ILS) or metformin could prevent or delay diabetes. A predefined secondary outcome of DPP was to determine if treatment effects varied by age.

RESULTS

At baseline, participants aged 60-85 years were leaner and had the best insulin sensitivity and lowest insulin secretion compared to younger age groups. Diabetes incidence rates did not differ by age in the placebo group, but ILS was more effective with increasing age (6.3, 4.9, and 3.3 cases per 100 person-years, in the 25-44, 45-59, and 60-85 year age groups, respectively; p(trend) =.007). Participants aged 60-85 years had the most weight loss and metabolic equivalent (MET)-hours of physical activity. The metformin group showed a trend toward higher diabetes incidence among older participants (6.7, 7.7, and 9.3 cases per 100 person-years in the 25-44, 45-59, and 60-85 year age groups, respectively; p(trend) =.07); and diabetes risk increased with age (hazard ratio [age 60-85 vs 25-44] 1.63, p =.02), after adjusting for the greater weight loss in the 60-85 year age group.

CONCLUSIONS

Lifestyle modification was exceptionally effective in preventing diabetes in older individuals; this finding was largely explained by greater weight loss and physical activity. The limited effectiveness of metformin in older persons may reflect age-related differences in insulin action and secretion. A lifestyle modification program can be recommended for older individuals at high risk for type 2 diabetes.