Hypoglycemia, With or Without Insulin Therapy, Is Associated With Increased Mortality Among Hospitalized Patients

OBJECTIVE: Hypoglycemia is associated with increased mortality in hospitalized patients. We investigated the relationship between spontaneous hypoglycemia versus insulin-associated hypoglycemia and mortality in hospitalized patients. RESEARCH DESIGN AND METHODS: Data for this retrospective cohort study were obtained from electronic databases of patients admitted between 1 April 2008 and 30 November 2010. Patients with one or more blood glucose values ≤50 mg/dL on point-of-care glucose testing were considered hypoglycemic. Patients treated with insulin were assumed to have insulin-associated hypoglycemia. Age-, sex-, and race-matched patients with all blood glucose values >70 mg/dL were selected as controls. The Charlson comorbidity index (CCI) was used to control for severity of illness. RESULTS: There were four groups: 1) noninsulin-treated hypoglycemia (NTH) (n = 135), 2) insulin-treated hypoglycemia (ITH) (n = 961), 3) noninsulin-treated control (NTC) (n = 1,058), and 4) insulin-treated control (ITC) (n = 736). Mortality was higher in the ITH group compared with the ITC group (20.3 vs. 4.5%, P < 0.0001), with a relatively higher CCI (1.8 vs. 1.5%, P < 0.0001), but much higher in the NTH group compared with the NTC group (34.5 vs. 1.1%, P < 0.0001), with much higher CCI (2.4 vs. 1.1%, P < 0.0001). Mortality was higher in the NTH group compared with the ITH group (P < 0.0001) but lower in the NTC group compared with the ITC group (P < 0.0001). After controlling for age, sex, CCI, and admission to the intensive care unit, insulin treatment was associated with a lower mortality among the hypoglycemic patients; hazard ratio of death in the ITH group relative to the NTH group was 0.34 (95% CI 0.25–0.47, P < 0.0001). CONCLUSIONS: Insulin-associated and spontaneous hypoglycemia are associated with increased mortality among hospitalized patients.