Diet and exercise in the prevention of diabetes.

The worldwide epidemic of obesity is being mirrored in worldwide epidemics of metabolic syndrome and of type 2 diabetes. The theme of the 2002 Future Forum conference is that these conditions are a certainty, given that the changing worldwide environment requires less physical activity for daily living and assures an abundant, energy-dense food supply at all times. This paper focuses on the roles of physical activity and weight reduction in reducing the risk for development of type 2 diabetes and the metabolic syndrome. The mechanisms by which obesity and detraining lead to insulin resistance and type 2 diabetes are discussed and, conversely, the mechanisms by which insulin resistance might be reversed by physical activity are addressed. Finally, the evidence from recent randomised clinical trials is reviewed. The Finnish Diabetes Prevention Study and the Diabetes Prevention Program in the USA both demonstrate that lifestyle change can significantly reduce the risk of development of type 2 diabetes in individuals with impaired glucose tolerance. Furthermore, these studies demonstrate that modest weight change and achievable physical activity goals can translate into significant risk reduction. Societies cannot afford to ignore the evidence of health benefit associated with physical activity and healthy weight in favour of medicating when morbidities develop. For a successful public health approach to chronic disease prevention, we cannot rely completely on pharmaceuticals, but must implement environmental changes to encourage healthy lifestyles.