Published in:
Open Access 01-04-2013 | Research
The effect of diabetes mellitus on the association between measures of glycaemiccontrol and ICU mortality: a retrospective cohort study
Published in: Critical Care | Issue 2/2013
Login to get accessAbstract
Introduction
In critical illness, four measures of glycaemic control are associated with ICUmortality: mean glucose concentration, glucose variability, the incidence ofhypoglycaemia (≤ 2.2 mmol/l) or low glucose (2.3 to 4.7 mmol/l). Underlyingdiabetes mellitus (DM) might affect these associations. Our objective was to studywhether the association between these measures of glycaemic control and ICUmortality differs between patients without and with DM and to explore the cutoffvalue for detrimental low glucose in both cohorts.
Methods
This retrospective database cohort study included patients admitted betweenJanuary 2004 and June 2011 to a 24-bed medical/surgical ICU in a teachinghospital. We analysed glucose and outcome data from 10,320 patients: 8,682 withoutDM and 1,638 with DM. The cohorts were subdivided into quintiles of mean glucoseand quartiles of glucose variability. Multivariable regression models were used toexamine the independent association between the four measures of glycaemic controland ICU mortality, and for defining the cutoff value for detrimental lowglucose.
Results
Regarding mean glucose, a U-shaped relation was observed in the non-DM cohort withan increased ICU mortality in the lowest and highest glucose quintiles (odds ratio= 1.4 and 1.8, P < 0.001). No clear pattern was found in the DMcohort. Glucose variability was related to ICU mortality only in the non-DMcohort, with highest ICU mortality in the upper variability quartile (odds ratio =1.7, P < 0.001). Hypoglycaemia was associated with ICU mortality inboth cohorts (odds ratio non-DM = 2.5, P < 0.001; odds ratio DM = 4.2,P = 0.001), while low-glucose concentrations up to 4.9 mmol/l wereassociated with an increased risk of ICU mortality in the non-DM cohort and up to3.5 mmol/l in the DM cohort.
Conclusion
Mean glucose and high glucose variability are related to ICU mortality in thenon-DM cohort but not in the DM cohort. Hypoglycaemia (≤ 2.2 mmol/l) wasassociated with ICU mortality in both. The cutoff value for detrimental lowglucose is higher in the non-DM cohort (4.9 mmol/l) than in the DM cohort (3.5mmol/l). While hypoglycaemia (≤ 2.2 mmol/l) should be avoided in bothgroups, DM patients seem to tolerate a wider glucose range than non-DMpatients.