The changes in the lean body mass are combined with a decline in plasma DHEA-S and IGF-1 concentration and a rise in plasma TNF-alpha concentrations and oxidative stress, which, as a result, may interact with the anthropometric changes- thereby triggering a worsening of insulin-mediated glucose uptake. The researchers report that age-related environmental factors- specifically, changes in diet quality and decline in the degree of physical activity- may be common causes that hasten the changes in insulin and insulin resistance that may develop as people age.

The researchers have found that the predictive role of plasma IGF 1 on age related decline in whole body glucose uptake. Thus, plasma IGF-1 concentration may have a modulating role on insulin action in older people. The researchers suggest that IGF-1 administration may be of benefit in insulin sensitivity in older adults.

Healthy centenarians have a preserved insulin action compared with younger individuals. Dr. Barbieri and colleagues from the University of Naples explain that, according to the remodeling theory of age, the preserved insulin action in centenarians might be the net result of the continuous adaptation of the body to the deleterious changes that occur over time. Such adaptive metabolic changes lead a positive health status in aging.