title: Critical illness-induced dysglycemia and the brain.
abstract: OBJECTIVE
  Dysglycemia is a characteristic feature of critical illness associated with adverse outcome. Whether dysglycemia contributes to brain dysfunction during critical illness and long-term neurological complications is unclear. We give an overview of glucose metabolism in the brain and review the literature on critical illness-induced dysglycemia and the brain.
  
  
  METHODS
  Medline database search using relevant search terms on dysglycemia, critical illness, acute brain injury/dysfunction, and randomized controlled trial.
  
  
  RESULTS
  Hyperglycemia has been associated with deleterious effects on the nervous system. Underlying mechanisms in critical illness remain largely speculative and are often extrapolated from knowledge in diabetes mellitus. Increased hyperglycemia-induced blood-brain barrier permeability, oxidative stress, and microglia activation may play a role and compromise neuronal and glial cell integrity. Hypoglycemia is feared as critically ill patients cannot recognize or communicate hypoglycemic symptoms, which furthermore are masked by sedation and analgesia. However, observational data on the impact of brief hypoglycemia on the brain in critical illness are controversial. Secondary analysis of two large randomized studies suggested neuroprotection by strict glycemic control with insulin during intensive care, with lowered intracranial pressure, reduction of seizures, and better long-term rehabilitation in patients with isolated brain injury, and reduced incidence of critical illness polyneuromyopathy in the general critically ill patient population. Several subsequent studies failed to reproduce neurological benefit, likely explained by methodological issues, which include divergent achieved glucose levels and inaccurate glucose monitoring tools.
  
  
  CONCLUSIONS
  Preventing hyperglycemia during critical illness holds promise as a neuroprotective strategy to preserve brain cell viability and prevent acute brain dysfunction and long-term cognitive impairment in survivors.
authors.affiliation: Clinical Department and Laboratory of Intensive Care Medicine, Division of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, 3000, Leuven, Belgium.
authors.forename: Romain
authors.initials: R
authors.lastname: Sonneville
authors.forename: Ilse
authors.initials: I
authors.lastname: Vanhorebeek
authors.forename: Heleen M
authors.initials: HM
authors.lastname: den Hertog
authors.forename: Fabrice
authors.initials: F
authors.lastname: Chrétien
authors.forename: Djillali
authors.initials: D
authors.lastname: Annane
authors.forename: Tarek
authors.initials: T
authors.lastname: Sharshar
authors.forename: Greet
authors.initials: G
authors.lastname: Van den Berghe
mesh_terms: D001786:Blood Glucose / Q000032:analysis; D001921:Brain / Q000378:metabolism*; D001927:Brain Diseases / Q000209:etiology*; D016638:Critical Illness; D044882:Glucose Metabolism Disorders / Q000150:complications* / Q000503:physiopathology; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents