Glucose is the main and preferred source of energy for the body. Poly- and oligosaccharides contained in foods are broken down into glucose. The liver and kidney also make glucose in the process of gluconeogenesis. In order to ensure the euglycemia necessary for metabolic processes in the cells glucose levels are carefully regulated to around 90 mg/dL (5 mM). The process of maintaining blood glucose at a steady-state level is called glucose homeostasis. This maintenance is achieved through a balance of several factors, including the rate of consumption and intestinal absorption of dietary carbohydrate, the rate of utilization of glucose by peripheral tissues and the loss of glucose through the kidney tubule, and the rate of removal or release of glucose by the liver. To avoid postprandial hyperglycemia (uncontrolled increases in blood glucose levels following meals) and fasting hypoglycemia (decreased in blood glucose levels during periods of fasting), the body can adjust glucose levels by a variety of cellular mechanisms. Important signals are conveyed by hormones, cytokines, and fuel substrates and are sensed through of cellular mechanisms. The liver plays a major role in blood glucose homeostasis by maintaining a balance between the uptake and storage of glucose via glycogenesis and the release of glucose via glycogenolysis and gluconeogenesis.
