Secretion of insulin during aging.

ecognition of and response to environmental challenge are expressed in part by the availability and efficacy of circulating hormones for R the modulation of intermediary metabolism in target cells. One example of such adaptive capability that changes during aging is the impact of dietary glucose on its insulin-sensitive metabolism by liver and peripheral tissues. This paper provides a critical review of published research that addresses the pivotal role of insulin secretion in that adaptive sequence during aging. According to most, but not all, published reports, the regulation of insulin secretion by glucose changes during aging. However, interpretation of these data is complicated by numerous factors, most prominent of which include 1) the extent to which it is possible to evaluate insulin secretion in vivo by measurement of hormone levels in peripheral blood; 2) the distribution of functionally heterogeneous populations of pancreatic islets of Langerhans; 3) distinctions between growth, obesity, and aging; and 4) the frequent failure to acknowledge relevant, previously published literature. The present paper will examine these data both in the context of such complications and from the perspective of the pursuit of further insight into the fundamental biological processes of aging that are expressed in the absence of disease and inappropriate lifestyle.