Hypoglycemia-associated Mortality Is Not Drug-associated but Linked to Comorbidities

OBJECTIVE: Although tight glucose control is used widely in hospitalized patients, there is concern that medication-induced hypoglycemia may worsen patient outcomes. We sought to determine if the mortality risk associated with hypoglycemia in hospitalized noncritically ill patients is linked to glucose-lowering medications (drug-associated hypoglycemia) or merely an association mediated by comorbidities (spontaneous hypoglycemia). METHODS: A retrospective cohort of patients admitted to the general wards of an academic center during 2007 was studied. The in-hospital mortality risk of a hypoglycemic group (at least 1 blood glucose <= 70 mg/dL) was compared with that of a normoglycemic group using survival analysis. Stratification by subgroups of patients with spontaneous and drug-associated hypoglycemia was performed. RESULTS: Among 31,970 patients, 3349 (10.5%) had at least 1 episode of hypoglycemia. Patients with hypoglycemia were older, had more comorbidities, and received more antidiabetic agents. Hypoglycemia was associated with increased in-hospital mortality (hazard ratio [HR], 1.67; 95% confidence interval [CI], 1.33-2.09; P < .001). However, this greater risk was limited to patients with spontaneous hypoglycemia (HR, 2.62; 95% CI, 1.97-3.47; P < .001) and not to patients with drug-associated hypoglycemia (HR, 1.06; 95% CI, 0.74-1.52; P = .749). After adjustment for patient comorbidities, the association between spontaneous hypoglycemia and mortality was eliminated (HR, 1.11; 95% CI, 0.76-1.64; P = .582). CONCLUSION: Drug-associated hypoglycemia was not associated with increased mortality risk in patients admitted to the general wards. The association between spontaneous hypoglycemia and mortality was eliminated after adjustment for comorbidities, suggesting that hypoglycemia may be a marker of disease burden rather than a direct cause of death. (C) 2011 Elsevier Inc. All rights reserved. . The American Journal of Medicine (2011) 124, 1028-1035