We performed a randomized controlled trial with the glucagon-like peptide-1 (GLP-1) receptor agonist exenatide as add-on to standard peri-operative insulin therapy in patients undergoing elective cardiac surgery. The aims of the study were to intensify peri-operative glucose control while minimizing the risk of hypoglycaemia and to evaluate the suggested cardioprotective effects of GLP-1-based treatments. A total of 38 patients with decreased left ventricular systolic function (ejection fraction ≤50%) scheduled for elective coronary artery bypass grafting (CABG) were randomized to receive either exenatide or placebo in a continuous 72-hour intravenous (i.v.) infusion on top of standard peri-operative insulin therapy. While no significant difference in postoperative echocardiographic variables was found between the groups, participants receiving exenatide showed improved peri-operative glucose control as compared with the placebo group (average glycaemia 6.4 ± 0.5 vs 7.3 ± 0.8 mmol/L; P <.001; percentage of time in target range of 4.5–6.5 mmol/L 54.8% ± 14.5% vs 38.6% ± 14.4%; P =.001; percentage of time above target range 39.7% ± 13.9% vs 52.8% ± 15.2%; P =.009) without an increased risk of hypoglycaemia (glycaemia <3.3 mmol/L: 0.10 ± 0.32 vs 0.21 ± 0.42 episodes per participant; P =.586). Continuous administration of i.v. exenatide in patients undergoing elective CABG could provide a safe option for intensifying the peri-operative glucose management of such patients.