In the Diabetes Prevention Program (DPP), lifestyle intervention with diet and exercise training significantly lowered the rate of progression from IGT to diabetes, and was particularly effective in older people. The mechanisms of lifestyle changes to prevent diabetes and the effects on beta-cell function remain unclear. Exercise is well-known to increase insulin sensitivity, although exercise effects on beta-cell function have not been specifically assessed. In a pilot study supported by local VA funds, one week of aerobic exercise training improved insulin sensitivity as expected, but also improved beta-cell function in sedentary older people with IGT, with no change in body weight/composition, fasting glucose or lipid/inflammatory parameters.