Hyperglycemia during critical illness is common and associated with increased mortality. Intensive insulin therapy has improved outcomes in some, but not all, intervention trials. It is currently unclear whether the benefits of treatment differ among specific patient populations.
To determine the association between hyperglycemia and risk-adjusted mortality in critically ill patients and in separate groups stratified by admission diagnosis. Secondarily, determine if mortality risk from hyperglycemia varies with ICU type, length of stay, or diagnosed diabetes.
Retrospective cohort study
173 U.S. medical, surgical, and cardiac ICUs
259,040 admissions from 10/2002–9/2005; unadjusted mortality, 11.2%
A two-level logistic regression model determined the relationship between glycemia and mortality. Age, diagnosis, co-morbidities and laboratory variables were used to calculate a predicted mortality, which was then analyzed with mean glucose to determine the association of hyperglycemia with hospital mortality.
Hyperglycemia was associated with increased mortality independent of illness severity. When compared to normoglycemic individuals (70–110 mg/dl), adjusted odds of mortality (odds ratio, [95% CI]) for mean glucose 111–145, 146–199, 200–300, > 300 mg/dl was, 1.31(1.26–1.36), 1.82(1.74–1.90), 2.13(2.03–2.25), and 2.85(2.58–3.14) respectively. Moreover, the adjusted odds of mortality related to hyperglycemia varied with admission diagnosis, demonstrating a clear association in some (acute myocardial infarction, arrhythmia, unstable angina, pulmonary embolism) and little or no association in others. Hyperglycemia was associated with increased mortality independent of ICU type, length of stay and diabetes.
The association between hyperglycemia and mortality implicates hyperglycemia as a potentially harmful and correctable abnormality in critically ill patients. The finding that hyperglycemia-related risk varied with admission diagnosis suggests differences in the interaction between specific medical conditions and injury from hyperglycemia. The design and interpretation of future trials should consider the primary disease states of patients and the balance of medical conditions in the ICU studied.