Effects of Glucose Variability on Short-Term Outcomes in Non-Diabetic Patients After Coronary Artery Bypass Grafting: A Retrospective Observational Study

Abstract

Postoperative hyperglycaemia has been shown to have adverse effects on patients after coronary artery bypass grafting surgery (CABG). However, whether glucose variability has an effect on patients' outcomes is still uncertain. The aim of this study is to explore the effects of glucose variability on short-term outcomes in non-diabetic patients undergoing coronary artery bypass grafting. This is a retrospective observational study utilising data collected after patients had left the hospital. This study was performed on 137 non-diabetic patients undergoing coronary artery bypass grafting from January 2011 to June 2013. Blood glucose at 72hours post operation was obtained and glucose variability was measured by mean postoperative blood glucose and mean of daily difference (MODD). Short-term outcomes included duration of intensive care unit (ICU) stay, mechanical ventilation time, length of hospital stay, and occurrence of arrhythmia. Patients with mean postoperative blood glucose ≥7.00mmol/L were defined as hyperglycaemic, and patients with MODD ≥1.40mmol/L were considered to be abnormal. Outcome variables were compared between patients in euglycaemic and hyperglycaemic groups, and between patients in normal and abnormal groups. In our study, patients with hyperglycaemia spent more time staying in ICU (p<0.01), and patients with large glucose variability (abnormal MODD) had higher incidences of arrhythmia (23% vs 4.2%, p<0.05). Regression analysis showed that MODD can affect occurrence of arrhythmia (p=0.004) and that mean postoperative blood glucose levels can affect duration of ICU stay (p<0.001). Patients' postoperative glucose variability after CABG is an important predictor of the negative outcomes regarding duration of ICU stay and occurrence of arrhythmia. Large glucose variability can have negative effects on short-term outcomes in patients.