Normal Glucose Homeostasis

Prolonged Fasting With prolongation of fasting, plasma insulin levels decrease while those of glucagon, catecholamines, growth hormone, and cortisol increase (Table 2.6). Consequently, plasma FFA, glycerol, and the ketone bodies – products  of FFA oxidation (beta hydroxybutyrate) – increase. Since hepatic glycogen stores become depleted by 60 h, virtually all of the glucose release at

Incretins: The Entero-insular Axis The concept that certain factors secreted from the intestinal mucosa in response to nutrients can stimulate the pancreas to release insulin was first introduced to explain the phenomenon of greater increase in plasma insulin levels in response to oral glucose load compared with the same load of glucose given intravenously (Table

Insulin Insulin regulates glucose metabolism by direct and indirect actions. Through binding to its receptors in the liver, kidney, muscle, and adipose tissue, insulin activates its signaling pathway which involves a complex cascade of protein kinases and regulatory proteins of which IRS-1 and IRS-2 are the most important (Table 2.2). This causes : Suppression of

Relative Changes in Glucose Fluxes Plasma glucose concentrations are determined by the relative rates at which glucose enters and leaves the circulation. Thus, the plasma glucose will increase only if the rate of entry exceeds its rate of exit and, conversely, plasma glucose level will decrease only if rates of exit exceed the rates of

Glucose: From Origins to Fates, Arterial plasma glucose values throughout a 24-h period average approximately 90 mg/dl, with a maximal concentration usually not exceeding 165 mg/dl such as after meal ingestion and remaining above 55 mg/dl such as after exercise or a moderate fast (60 h). This relative stability contrasts with the situation for other