Association of blood glucose levels with in-hospital mortality and 30-day readmission in patients undergoing invasive cardiovascular surgery

Objective: This study aimed to evaluate the association of mean and maximum blood glucose (BG) levels with in-hospital mortality and 30-day hospital readmission among patients in the intensive care unit (ICU) undergoing invasive cardiovascular (CV) surgery. Research design and methods: The retrospective database analysis consisted of data from 3132 patients from 17 hospitals who underwent an invasive CV surgery during 1/2000-12/2006. Patients with hyperglycemia were identified based on serum BG levels recorded from 12 hours prior to and 24 hours after ICU admission. Separate logistic regression models were used to examine the association of mean and maximum BG levels to in-hospital mortality and 30-day readmission, adjusting for patient demographics, comorbidities and laboratory values. Results: The adjusted odds ratio (OR) for in-hospital mortality was 1.07 (95% CI: 1.01-1.12; p<.001) for every 0.56-mmol/L increase in mean BG, and OR -1.06 (95% CI: 1.03-1.08, p<.001) for every 0.56-mmol/L increase in maximum BG. Mean BG was not associated with 30-day readmission while maximum BG had a borderline association: OR = 1.02 (95% CI: 1.00-1.03, p=.06). Limitation: The results are not generalizable to all cardiovascular surgical patients since only those undergoing invasive procedures were included in the study. Conclusions: Higher mean and maximum BG levels were associated with increased risk of in-hospital mortality but not with 30-day readmission. Further research is needed to identify optimal BG targets and the effects of avoiding extreme hyperglycemia on patient outcomes.