Prevention of type 2 diabetes by dietary patterns: a systematic review of prospective studies and meta-analysis.

Lifestyle intervention may reduce the risk of type 2 diabetes. The aim of this study was to investigate the role of dietary patterns in the prevention of type 2 diabetes. We did an electronic search through November 30, 2009, for prospective studies that evaluated the role of dietary patterns in type 2 diabetes prevention. Ten large prospective studies were identified, comprising more than 190,000 subjects free of diabetes at baseline, followed for a time ranging from 2 to 23 years, and 8,932 cases of incident diabetes. All ten studies showed consistent results: Relative risk reduction of type 2 diabetes ranged from 83% to 15%. Overall, adherence to a healthy dietary pattern was associated with reduced risk of developing type 2 diabetes: Combined mean difference  = -0.39, 95% confidence interval (CI) -0.54 to -0.24. The reduced risk of developing type 2 diabetes was still present after sensitivity analysis (-0.34, 95% CI -0.44 to -0.24). Dietary patterns characterized by high consumption of fruit and vegetables, whole grains, fish, and poultry, and by decreased consumption of red meat, processed foods, sugar-sweetened beverages, and starchy foods may retard the progression of type 2 diabetes. Healthy diets can help people to live more years without type 2 diabetes.