In healthy individuals, maintenance of a normal plasma glucose concentration depends upon:
- A normal endocrine system for integrating and modulating substrate mobilization, interconversion, and utilization
- Functionally intact enzymes for glycogenolysis, glycogen synthesis, glycolysis, gluconeogenesis, and utilization of other metabolic fuels for oxidation and storage
- An adequate supply of endogenous fat, glycogen, and potential gluconeogenic substrates (eg, amino acids, glycerol, and lactate)
Adults are capable of maintaining a near-normal blood glucose concentration, even when totally deprived of calories for weeks or, in the case of obese subjects, months . In contrast, healthy neonates and young children are unable to maintain normal plasma glucose concentrations after even a short fast (24 to 36 hours) and exhibit a progressive decline in plasma glucose concentration to hypoglycemic values [2,3].
Abnormalities in hormone secretion, substrate interconversion, and mobilization of metabolic fuels contribute to abnormalities in glucose production and utilization that ultimately result in hypoglycemia in children. The appropriate evaluation and treatment of the child with hypoglycemia require an understanding of the factors that regulate glucose metabolism and the unique aspects of glucose metabolism in infants and young children.
Glucose homeostasis and the diagnostic approach to hypoglycemia in infants and children will be discussed here. The causes of hypoglycemia and hypoglycemia in neonates are discussed separately. (See "Etiology of hypoglycemia in infants and children" and "Neonatal hypoglycemia".)