Causes and consequences of hyperglycemia in critical illness.

PURPOSE OF REVIEW: This article reviews recent epidemiologic and intervention studies addressing the impact of hyperglycemia on morbidity and mortality in critically ill patients. It also discusses a growing body of literature examining why elevated blood glucose occurs in hospitalized patients without previously recognized diabetes. RECENT
FINDINGS: Hyperglycemia is highly prevalent in the intensive care unit. Numerous observational studies have demonstrated the association between hyperglycemia and adverse outcomes, independent of pre-existing diabetes. Intervention trials of insulin therapy are limited but overall demonstrate that glucose lowering significantly improves outcomes. The ideal target for blood glucose and the population that would benefit most from intervention remain controversial. Less frequently studied than the consequences, the causes of hyperglycemia occurring during critical illness remain unclear. Although glucose abnormalities in hospitalized patients have traditionally been explained by mediators of stress, a growing body of evidence has examined whether underlying defects in glucose metabolism may also be important contributors.
SUMMARY: In general, evidence suggests that hyperglycemia is a potentially correctable abnormality that has deleterious effects in critically ill individuals. Hyperglycemic patients without previously recognized diabetes appear to be particularly vulnerable, and thus further examination of the mechanisms underlying the development of elevated blood glucose is warranted.