Based on my current VA RCDA project and the pilot study results, this VA CDA-2 proposal will test in detail the novel overall hypothesis that lifestyle intervention with aerobic exercise training leads to improved beta-cell function in human age-related glucose intolerance. The potential mechanisms of the age-associated decline in beta-cell function and whereby exercise training may improve beta-cell function will also be explored. Beta-cell function will be examined in relation to expected improvements in insulin sensitivity, and the effects of exercise will be isolated with weight maintenance and nutritional balance. The time course of exercise effects over three months, the acute and chronic effects of exercise training on beta-cell function, the effects of high vs. low intensity exercise training, and different important components of beta-cell function will be examined. The interaction between exercise training effects on beta-cell function in older people with IGT and potential mediators including free fatty acids (FFA)/FFA composition, intraabdominal fat, adipocytokines, and incretin hormones will be examined.