Aging in mammals has often been associated with decreased insulin secretion and a subsequent deterioration in the ability to maintain glucose homeostasis. However, recent studies have demonstrated that factors such as disease, obesity, and physical activity more closely reflect diminished insulin secretion rather than aging per se. Thus, the purpose of this article is to review recent studies of how biological aging, i.e. the process independent of disease states such as type II diabetes, may affect insulin secretion. To this end, this review will address the impact of aging on insulin secretion in terms of in vivo and in vitro assessment, as well as possible age-related alterations in the hormonal and neural regulation of insulin secretion. Finally, this review describes some evidence that alterations in the functional heterogeneity of the beta-cell population may represent a means by which the endocrine pancreas is able to maintain appropriate insulin secretion during senescence.