Hyperglycaemia and pulmonary infection

Abstract

Pathophysiological stress from acute illness causes metabolic disturbance, including altered hepatic glucose metabolism, increased peripheral insulin resistance and hyperglycaemia. Acute hyperglycaemia is associated with increased morbidity and mortality in patients in intensive care units and patients with acute respiratory disease. The present review will consider mechanisms underlying this association. In normal lungs the glucose concentration of airway secretions is approximately 10-fold lower than that of plasma. Low airway glucose concentrations are maintained against a concentration gradient by active glucose transport. Airway glucose concentrations become elevated if normal homeostasis is disrupted by a rise in blood glucose concentrations or inflammation of the airway epithelium. Elevated airway glucose concentrations are associated with and precede increased isolation of respiratory pathogens, particularly methicillin-resistant Staphylococcus aureus, from bronchial aspirates of patients intubated on intensive care. Markers of elevated airway glucose are associated with similar patterns of respiratory infection in patients admitted with acute exacerbations of chronic obstructive pulmonary disease. Glucose at airway concentrations stimulates the growth of respiratory pathogens, over and above the effect of other nutrients. Elevated airway glucose concentrations may also worsen respiratory disease by promoting local inflammation. Hyperglycaemia may thus promote pulmonary infection, at least in part, by an effect on airway glucose concentrations. Therapeutic options, including systemic control of blood glucose and local manipulation of airway glucose homeostasis, will be considered.

T2R38 taste receptor polymorphisms underlie susceptibility to upper respiratory infection

“…Bacteria were then centrifuged, washed 3 times with PBS plus 0.5 mM glucose, resuspended at 0.1 OD in the same solution, and incubated at 37°C with shaking. This glucose concentration was chosen because physiological ASL glucose concentrations have been demonstrated to be approximately 10% of serum glucose, which is normally approximately 5-8 mM (78)(79)(80)(81). Aliquots of this solution were taken at 30 minutes, 2 hours, and 6 hours and then centrifuged and filter sterilized as described above.…”

Stress Hyperglycemia in Pediatric Critical Illness: The Intensive Care Unit Adds to the Stress!

“…In turn, SH likely prolongs the duration of mechanical ventilation directly via lung damage and indirectly through the development of critical illness myopathy. 59,60 Poor control of hyperglycemia in children with type 1 diabetes mellitus and cystic fibrosis is associated with worsening of pulmonary function. 61,62 It is conceivable that similar mechanisms may play a role during critical illness in children.…”

Screening for cystic fibrosis-related diabetes: a systematic review.

“…It may also foster virulence. 117 Increased glycosylation of both immune proteins and epithelial cells might further impair local defences. 118 Optimising glycaemic control, and so maintenance of normal or near-normal concentration of glucose in airways secretions, could be a significant factor protecting patients with CF from intercurrent and chronic microbial infection.…”

“…117 The air spaces are lined with a thin layer of fluid which normally contains little or no glucose, 118 but the level can be increased by both hyperglycaemia and inflammation, both of which occur in CF. The presence of glucose encourages the proliferation of colonising and infective microorganisms.…”