Review: deterioration of glucose tolerance with age: the role of insulin resistance.

Glucose tolerance is determined by the balance of insulin secretion and insulin action and deteriorates with age. Insulin secretion does not appear to be reduced with increasing age, but many recent studies have demonstrated insulin resistance in healthy elderly subjects. However, this has not been a universal finding and the reasons for the discrepant results probably include general health, physical training, changes of liver size and delays in carbohydrate absorption. When confounding factors, particularly physical activity, are taken into account there appears to be little or no change in insulin action with age. Delays in monosacharride absorption may play a role. Maintaining physical fitness throughout middle and older age and so reducing hyperinsulinaemia may have benefits on reducing vascular disease.