Effect of Age on the Emergence of Insulin Resistance
Insulin sensitivity declines with aging, and manifests itself with a progressive increase in fasting and postprandial plasma insulin concentrations (Reaven and Reaven 1985; Davidson, 1979; Weingard et al., 1990). Typically in humans, plasma glucose levels are maintained at a normal range during fasting and postprandially; however, higher insulin levels are required to appropriately regulate endogenous glucose production and to avoid hyperglycemia (Fraze et al., 1987; Meneilly et al., 1987; Pagano et al., 1984; Robert et al., 1982; Jackson et al., 1988). As reviewed in other chapters, insulin resistance may further develop into a glucose intolerance state and type 2 diabetes mellitus (DM2). This is a process that is accelerated with aging; the incidence of DM2 reaching 30% in some older populations.