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

Abstract

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.