Mean glucose level is not an independent risk factor for mortality in mixed ICU patients

Objective: To find out if there is an association between hyperglycaemia and mortality in mixed ICU patients. Design and setting: Retrospective cohort study over a 2-year period at the medical ICU of a university hospital. Measurements: Admission glucose, maximum and mean glucose, length of stay, mortality, insulin therapy and Apache-II score. Results: In 1085 consecutive patients, ICU-and hospital mortality were 20 and 25%, respectively. The total number of blood glucose measurements was 10.012. Admission glucose was 7.9 ± 4.5 mmol/l (mean ± SD), mean glucose 7.5 ± 2.9 and maximum glucose 10.0 ± 5.4 mmol/l. Median ICU length of stay (LOS) was 3.0 days (range 2.0-6.0 days, IQR), and hospital LOS was 16 days (range 7-32 days). In 28% of patients insulin treatment was started. Median Apache-II score was 13. 68% of patients were mechanically ventilated. Univariate analysis showed an association with ICU mortality for mean glucose (non-survivors 8.6 ± 4.3 vs 7.2 ± 2.4 survivors), maximum glucose (11.7 ± 5.9 vs 9.6 ± 5.2, non-survivors vs survivors, respectively), use of insulin (mortality 29 vs 17% in patients not using insulin) and age (61 vs 55.7 years). Gender and a history of diabetes mellitus were not associated with mortality. In a multivariate model, the Apache-II score was the only variable associated with mortality independent of other variables, including mean blood glucose. Conclusion: In this retrospective study mean glucose level was not an independent risk factor for mortality in mixed ICU patients.