Background: There is a high prevalence of diabetes and impaired glucose tolerance (IGT) in the older population. Normal aging is associated with insulin resistance and impaired insulin secretion, with greater defects in people with IGT. Short-term exercise has been found to increase insulin sensitivity, but little is known about acute exercise effects on -cell function in older people with IGT.

Methods: We assessed the effects of 7 consecutive days of supervised aerobic exercise (1 hr/day at 60–70% heart rate reserve) in 12 sedentary older people with IGT. Screening included oral glucose tolerance test, stress/VO2 test, and DEXA scan. Participants had a frequently sampled IV glucose tolerance test (FSIGT) at baseline and 15–20 hrs post 7th exercise session. Insulin sensitivity (S_I), IV glucose tolerance (Kg), acute insulin response to glucose (AIRg), disposition index (DI, AIRg x S_I), a measure of -cell function in relation to insulin resistance, were calculated.

Results: Exercise was well-tolerated. Body weight, fasting glucose/insulin, and Kg were unchanged with exercise. S_I increased by 59%, AIRg decreased by 12%, and DI increased by 31%. There was no significant change in fasting lipid, catecholamine, leptin or adiponectin levels.

Conclusions: Short-term exercise not only improved insulin resistance, but also significantly enhanced -cell function in older people with IGT. These effects of short-term exercise on -cell function cannot be explained by changes in body weight or in circulating levels of lipids, leptin, adiponectin, or catecholamines.