Chapter

Hypoglycaemia: assessment and management

Andrew Cotterill, David Cowley and Ristan Greer

in Oxford Textbook of Endocrinology and Diabetes

Second edition

Published on behalf of Oxford University Press

ISBN: 9780199235292
Published online July 2011 | e-ISBN: 9780199608232 | DOI: http://dx.doi.org/10.1093/med/9780199235292.003.7033

Series: Oxford Textbooks

Hypoglycaemia: assessment and management

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Hypoglycaemia is defined as a blood glucose level less than 2.6 mmol/l. This is based on the consistent impairment of central nervous system function observed in subjects when blood glucose levels are below this (1). Glucose homeostatic mechanisms should maintain blood glucose level to preserve cognitive function. Hypoglycaemia triggers protective glucose homeostatic mechanisms and persistent hypoglycaemia is the result of a failure of homeostasis. This is a medical emergency with serious short- and long-term consequences, which result from a reduced supply of glucose to the brain. Recurrent and persistent hypoglycaemia does cause significant morbidity and death due to brain damage. In an adult, after recovery of glucose levels, neurological impairment usually recovers over minutes to hours. In children, the duration of hypoglycaemia leading to permanent damage is not known, but is presumed to depend on the age of the child, the frequency of hypoglycaemia, the degree and the rapidity of the fall in glucose, concurrent circumstances such as infection, trauma and hypoxia, the degree of resilience of the brain tissue at the current stage of development. and the energy demands of the particular parts of the brain. The reasons for the increased sensitivity in children appear to relate to the higher energy requirements and immaturity of the homeostatic mechanisms of the brain. In congenital hyperinsulinism of infancy (CHI) the rates of severe neurological impairment remain high at 20–50%, permanent neurological impairment with damage occurring mainly in the cerebral cortex, hippocampus, and caudate putamen. Appropriate long term management of hypoglycaemia requires the correct diagnosis, and this depends on obtaining ‘critical blood and urine samples’ during a hypoglycaemic episode. In the first 48 h of life 20% of normal full–term infants have a blood glucose level <2.6 mmol/l (2), after this it is relatively uncommon in infancy and childhood with the incidence of various underlying diagnoses varying with age. The causes of hypoglycaemia can be classified into five groups: ◆ excess insulin (or insulin-like factors) for the given circumstances ◆ lack of one or more of the counter regulatory hormones (cortisol, growth hormone) ◆ disturbance of intermediate metabolism causing impairment of gluconeogenesis and/or glycogenolysis ◆ disturbance of fat breakdown or ketone body formation or utilization ◆ lack of nutrient sufficient for current energy demands

Chapter.  8007 words.  Illustrated.

Subjects: Endocrinology and Diabetes

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