Association between hypoglycemia and inpatient mortality and length of hospital stay in hospitalized, insulin-treated patients.

OBJECTIVE: To assess the impact of hypoglycemia on clinical outcomes among hospitalized, insulin-treated patients.

METHODS: In a retrospective study, hospitalizations in 2005-2007 were identified from a US inpatient electronic medical records database. All encounters for insulin-treated patients with valid blood glucose measurement were included, except for those with a length of stay <24 hours or >30 days. In an encounter-based analysis, associations between hypoglycemic (glucose ≤70 mg/dL) or severe hypoglycemic (glucose ≤50 mg/dL) episodes and inpatient mortality, ischemic events, neurologic complications, and length of stay were evaluated.

RESULTS: Among 107,312 admissions, hypoglycemia occurred in 21,561 (20%) and severe hypoglycemia in 7539 (7%). Inpatient mortality occurred in 6.5% of hospitalizations with hypoglycemia and 3.8% of those without (p < 0.001). Inpatient mortality occurred in 7.6% of hospitalizations with a severe hypoglycemic event. Ischemic events (8.1 vs. 8.0%) and neurologic complications (3.8 vs. 3.7%) were similar in hospitalizations with and without a hypoglycemic event, respectively. In multivariate logistic regression analyses adjusting for age, gender, and selected comorbidities, hypoglycemia was associated with a significant increase in inpatient mortality risk (adjusted odds ratio (OR) = 1.66 [95% CI: 1.55, 1.78]). Similar results were observed with severe hypoglycemia (adjusted OR = 1.44 [1.38, 1.52]). Length of stay was increased in hospitalizations with hypoglycemia (median [interquartile range]: 8.2 days [4.9, 13.9] vs. 5.2 days [3.1, 8.3]; p < 0.0001).

LIMITATIONS: Due to the nature of the data source, some data of interest were not available, including insulin dose and dose regimen, outpatient medical histories (including diabetes history), pre-hospitalization medications, and cause of death.

CONCLUSIONS: Hypoglycemia was common among hospitalized patients receiving insulin and, while a direct causal relationship cannot be assumed, was associated with an increased risk of inpatient mortality and increased length of hospital stay. Hypoglycemia is an undesirable event and efforts to minimize in-hospital hypoglycemic events are warranted across the spectrum of hospitalized patients.