Background Disturbances of glucose metabolism are important risk factors for coronary artery disease and are associated with an increased mortality risk. The aim was to investigate the association between preoperative disturbances of glucose metabolism and long-term all-cause mortality after coronary artery bypass grafting (CABG).

Methods Patients undergoing a first isolated CABG in 2005–2013 were included. All patients without previously known diabetes underwent an oral glucose tolerance test (OGTT) before surgery. They were categorised as having normal glucose tolerance (NGT), pre-diabetes (impaired glucose tolerance and/or impaired fasting glucose) or newly discovered diabetes. Data were collected from nationwide healthcare registers. Cox regression was used to calculate adjusted HR with 95% CI for death in patients with pre-diabetes and diabetes, using NGT as reference.

Results In total, 497 patients aged 40–86 years were included. According to OGTT, 170 (34%) patients had NGT, 219 (44%) patients with pre-diabetes and 108 (22%) patients had newly discovered diabetes. Baseline characteristics were similar between the groups except for slightly higher age among patients with newly discovered diabetes. There were 133 (27%) deaths during a mean follow-up time of 10 years. The cumulative 10-year survival was 77% (69%–83%), 83% (77%–87%) and 71% (61%–79%) in patients with NGT, pre-diabetes and newly discovered diabetes, respectively. There was no significant difference in all-cause mortality between the groups after multivariable adjustment.

Conclusion In this study, patients with pre-diabetes or newly discovered diabetes prior to CABG had similar long-term survival compared with patients with NGT.