Insulin actions in vivo: glucose metabolism

Glucose is an essential nutrient for the body's energy requirements and plasma glucose levels are tightly regulated to avoid extremes of hyper- and hypoglycemia. Under basal postabsorptive conditions, endogenous (liver and kidney) glucose production is closely matched to total body glucose uptake and the fasting plasma glucose concentration is maintained between a very narrow range, 70-90 mg dL^-1. Following ingestion of a meal the combination of hyperglycemia plus hyperinsulinemia conspire to suppress endogenous glucose release and stimulate glucose uptake by insulin-sensitive tissues, including muscle, liver, and adipocytes. Each cell type contains a specific glucose transporter and hexokinase that is designed to match organ blood flow and glucose uptake to the metabolic needs of tissue.