A 68-year-old female with a history of type 2 diabetes mellitus is admitted to the ICU with pancreatitis. Her ICU course is notable for vasodilatory shock requiring vasopressors, respiratory failure requiring mechanical ventilation, renal failure requiring renal replacement therapy, and multiple episodes of hypoglycemia (blood glucose <80 mg/dL). TRUE statements include:
A. Hypoglycemia is a cause of mortality in critically ill patientsCorrect Answer: C
The NICE-SUGAR trial showed that patients receiving intensive glucose control (target blood glucose 81-108 mg/dL) had more episodes of severe hypoglycemia (blood glucose ≤40 mg/dL) than patients in the conventional glucose control (blood glucose <180 mg/dL) group. A subsequent study using data from the NICE-SUGAR database examined the relationship between hypoglycemia and mortality. This study found an increased mortality in patients with hypoglycemia. Furthermore, patients with severe hypoglycemia (blood glucose <40 mg/dL) had a higher risk of death when compared to normoglycemic patients than patients with moderate hypoglycemia (blood glucose between 40 and 79). Patients with more than 1 day of hypoglycemia were also more likely to die than those with 1 day of hypoglycemia. Although hypoglycemia occurred more frequently in patients in the intensive glucose control group, the association between hypoglycemia and death was similar in the two groups.
Patients who had an ICU stay of 7 days or longer were more likely to have moderate/severe hypoglycemia than those whose ICU length of stay was shorter. Patients with moderate and severe hypoglycemia also had an increased risk of death from vasodilatory shock when compared with patients who did not have hypoglycemia.
This study did not show a difference between risk of death with moderate and severe hypoglycemia in patients with and without diabetes. However, another study showed that poorly controlled diabetic patients (as reflected by Hgb A1c level within a 3-month period preceding ICU admission) were more likely to have moderate/severe hypoglycemia and higher risk of death.
Although these studies show an association between hypoglycemia and death, they do not prove causality. The current consensus for blood sugar management in critically ill patients is to target a blood sugar between 140 to 180 mg/dL. Patients with poorly controlled diabetes may benefit from closer blood sugar monitoring as they are more likely to become hypoglycemic and have poorer outcomes.
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