Blood Glucose

Synonyms

Blood sugar

Definition

Blood glucose concentrations are maintained by tight regulation of glucose production and glucose utilization by insulin- and non-insulin-dependent tissues. Blood glucose levels are usually in the range of 70–99 mg/dL during fasting. Postprandial blood glucose levels might rise up to 140 mg/dl transiently. Blood glucose less than 70 mg/dL is considered hypoglycemia. Three main sources of glucose include gut absorption after ingestion of carbohydrates, endogenous glucose production from glycogenolysis (breakdown of glycogen), and gluconeogenesis (formation of glucose from amino acids, lactate, and glycerol). Only the liver and kidney provide the enzymes necessary for these two processes. The brain depends on continuous plasma glucose supply and cannot use free fatty acid as an energy source. Normoglycemia is essential to preserve cognitive functions, and long-term hypoglycemia or hyperglycemia can result in serious neurological sequela. Tissue-specific...