Glucose variability and mortality in patients with sepsis

Abstract

Objective: Treatment and prevention of hyperglycemia has been advocated for subjects with sepsis. Glucose variability, rather than the glucose level, has also been shown to be an important factor associated with in-hospital mortality, in general, critically ill patients. Our objective was to determine the association between glucose variability and hospital mortality in septic patients and the expression of glucose variability that best reflects this risk.

Design: Retrospective, single-center cohort study.

Setting: Academic, tertiary care hospital.

Patients: Adult subjects hospitalized for >1 day, with a diagnosis of sepsis were included.

Interventions: None.

Measurements: Glucose variability was calculated for all subjects as the average and standard deviation of glucose, the mean amplitude of glycemic excursions, and the glycemic lability index. Hospital mortality was the primary outcome variable. Logistic regression was used to determine the odds of hospital death in relation to measures of glucose variability after adjustment for important covariates.

Main results: Of the methods used to measure glucose variability, the glycemic lability index had the best discrimination for mortality (area under the curve = 0.67, p < 0.001). After adjustment for confounders, including the number of organ failures and the occurrence of hypoglycemia, there was a significant interaction between glycemic lability index and average glucose level, and the odds of hospital mortality. Higher glycemic lability index was not independently associated with mortality among subjects with average glucose levels above the median for the cohort. However, subjects with increased glycemic lability index, but lower average glucose values had almost five-fold increased odds of hospital mortality (odds ratio = 4.73, 95% confidence interval = 2.6-8.7) compared with those with lower glycemic lability index.

Conclusions: Glucose variability is independently associated with hospital mortality in septic patients. Strategies to reduce glucose variability should be studied to determine whether they improve the outcomes of septic patients.

Figure 1

Cohort selection criteria. Patient records were selected from all inpatient records from 2005 based on discharge diagnoses. Numbers of subjects and reasons for exclusion are reported. The 21 subjects listed as having “limited glucose data” had only one value for glucose recorded during their hospitalization, thus making the calculation of variability impossible. LOS, length of stay.

Figure 2

Observed mortality for the whole sepsis cohort by glucose measure. All hospital measures of glucose were used to generate glycemic lability index (GLI). From this the expected mortality was generated across the range of observed values of glucose. Each decile contains approximately 125 subjects.