Both blood glucose and lactate are well-known predictors of organ dysfunction and mortality in critically ill patients. Previous research has shown that concurrent adjustment for glucose and lactate modifies the relationship between these variables and patient outcomes, including blunting of the association between blood glucose and patient outcome. We aim to investigate the relationship between ICU admission blood glucose and hospital mortality while accounting for lactate and diabetic status. Across 43,250 ICU admissions, weighted to account for missing data, we assessed the predictive ability of several logistic regression and generalised additive models that included blood glucose, blood lactate and diabetic status. We found that inclusion of blood glucose marginally improved predictive performance in all patients: AUC-ROC 0.665 vs 0.659, with a greater degree of improvement seen in non-diabetics: AUC-ROC 0.675 vs 0.663. Inspection of the estimated risk profiles revealed the standard U-shaped risk profile for blood glucose was only present in non-diabetic patients after controlling for blood lactate levels. Future research should aim to utilise observational data to estimate whether interventions such as insulin further modify this effect, with the goal of informing future RCTs of interventions targeting glycaemic control in the ICU.

The authors have declared no competing interest.

This study (via a PhD scholarship) was funded by UNSW Sydney, eHealth NSW and the Commonwealth Scientific and Industrial Research Organisation (CSIRO).

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Institutional ethics for the research project was obtained from UNSW Sydney - HC220829.

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The data underlying this article are freely available at https://eicu-crd.mit.edu/ and can be accessed following completion of the required training and data usage agreements.

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