Chapter 92 - Hypoglycemia from Kliegman : Nelson Textbook of Pediatrics

Glucose has a central role in fuel economy and is a source of energy storage in the form of glycogen, fat, and protein (see Chapter 87 ). Glucose, an immediate source of energy, provides 38 mol of adenosine triphosphate (ATP) per mol of glucose oxidized. It is essential for cerebral energy metabolism because it is usually the preferred substrate and its utilization accounts for nearly all the oxygen consumption in the brain. Cerebral glucose uptake occurs through a glucose transporter molecule or molecules that are not regulated by insulin. Cerebral transport of glucose is a carrier-mediated, facilitated diffusion process that is dependent on blood glucose concentration. Deficiency of brain glucose transporters can result in seizures because of low cerebral and cerebrospinal fluid (CSF) glucose concentrations (hypoglycorrhachia) despite normal blood glucose levels. To maintain the blood glucose concentration and prevent it from falling precipitously to levels that impair brain function, an elaborate regulatory system has evolved.