ORIGINAL ARTICLE
Hypoglycemia and Outcome in Critically Ill Patients

https://doi.org/10.4065/mcp.2009.0394Get rights and content

OBJECTIVE

To determine whether mild or moderate hypoglycemia that occurs in critically ill patients is independently associated with an increased risk of death.

PATIENTS AND METHODS

Of patients admitted to 2 hospital intensive care units (ICUs) in Melbourne and Sydney, Australia, from January 1, 2000, to October 14, 2004, we analyzed all those who had at least 1 episode of hypoglycemia (glucose concentration, <81 mg/dL). The independent association between hypoglycemia and outcome was statistically assessed.

RESULTS

Of 4946 patients admitted to the ICUs, a cohort of 1109 had at least 1 episode of hypoglycemia (blood glucose level, <81 mg/dL). Of these 1109 patients (22.4% of all admissions to the intensive care unit), hospital mortality was 36.6% compared with 19.7% in the 3837 nonhypoglycemic control patients (P<.001). Even patients with a minimum blood glucose concentration between 72 and 81 mg/dL had a greater unadjusted mortality rate than did control patients (25.9% vs 19.7%; unadjusted odds ratio, 1.42; 95% confidence interval, 1.12-1.80; P=.004.) Mortality increased significantly with increasing severity of hypoglycemia (P<.001). After adjustment for insulin therapy, hypoglycemia was independently associated with increased risk of death, cardiovascular death, and death due to infectious disease.

CONCLUSION

In critically ill patients, an association exists between even mild or moderate hypoglycemia and mortality. Even after adjustment for insulin therapy or timing of hypoglycemic episode, the more severe the hypoglycemia, the greater the risk of death.

Section snippets

PATIENTS AND METHODS

Data collection and data analysis were approved by the local institutional ethics committees, which waived the need for informed consent. The Austin Hospital Ethics Committee approved this investigation.

We conducted the study in 2 teaching hospital ICUs in Melbourne and Sydney, Australia. All patients admitted from January 1, 2000, to October 14, 2004, were included in the study. Both ICUs admitted adult medical and surgical patients, including cardiac and neurosurgical cases. We studied all

RESULTS

We studied 4946 ICU patients with 125,036 glucose measurements (mean measurements/day, 5.7) and identified 1109 patients (22.4%) with at least 1 episode of hypoglycemia. Their unadjusted hospital mortality was greater than that of the 3837 nonhypoglycemic patients (controls) (36.6% vs 19.7%; unadjusted OR, 2.35; 95% CI, 2.03-2.72; P<.001). A multivariate model for mortality was found to be highly discriminatory (area under the curve [AUC], 0.80) and well calibrated (Hosmer-Lemeshow statistic, P

DISCUSSION

We sought to understand the epidemiology, severity, duration, recovery, and outcome associations of hypoglycemiain critically ill patients. We found that 22.4% of patients experienced at least one blood glucose value less than 81 mg/dL and 2.1% sustained at least one value less than 40 mg/dL. Hypoglycemia had an increased adjusted risk of hospital death, and its severity (whether spontaneous or insulin-associated) was independently associated with higher mortality. In contrast, among patients

CONCLUSION

We found an independent association between even mild or moderate hypoglycemia and mortality. This association persisted after adjustment for insulin therapy. In hypoglycemic patients, severity of hypoglycemia was independently associated with mortality, but severity of hyperglycemia was not. The association between hypoglycemia and mortality remained even after patients who had hypoglycemia in the 24 hours before death were excluded. One-third of episodes of hypoglycemia were

Acknowledgments

We acknowledge the assistance of the ICU nurses who performed all measurements.

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      Low blood glucose has various causes and is called as hypoglycemia when glucose levels in blood are <2.8 mmol/L (<3.9 mmol/L in diabetic patients) along with particular signs and symptoms.[20] The incidence of hypoglycemia is 18–65% in critically ill patients[14] and the mortality is approximately 35.4–50.2% in patients with severe hypoglycemia.[7,21] Hypoglycemia is independently associated with increased mortality in critically ill patients and the risk increases with time and number of hypoglycemic episodes.[7]

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    This study was supported by a grant from the Austin Hospital Intensive Care Trust Fund.

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