Rationale and strategies for improving glycaemic control in diabetic patients undergoing cardiac surgery: a narrative review.

Background and Objective: The global prevalence of diabetes mellitus has markedly risen in recent years. Consequently, there has been a rise in the number of patients with diabetes undergoing cardiac surgery. Despite the existence of national and international guidelines to improve surgical outcomes in patients with diabetes, perioperative diabetes management optimisation remains inadequate resulting in these patients experiencing increased rates of surgical morbidity and mortality. This review aims to evaluate outcomes following cardiac surgery in patients with diabetes and assess strategies to enhance preoperative and perioperative optimization and postoperative outcomes. Methods: A comprehensive literature search was performed for articles concerning perioperative management of diabetes in patients undergoing cardiac surgery as well as postoperative complications related to diabetes in addition to interventions utilised to optimize outcomes. Key Content and Findings: Principle findings were extracted and synthesized. Patients with diabetes undergoing cardiac surgery exhibit increased perioperative complications, higher in-hospital mortality rates and inferior long-term survival. A key facilitator is specifically poor glycemic control, with glycated haemoglobin (HbA1c) serving as a predictive marker. However, measuring preoperative HbA1c is not routine, and there is no established threshold for deferring elective surgery. Preoperatively, emphasis should be placed on lowering the patient's HbA1c through optimized medical management and continuous glucose monitoring. Intraoperatively, continuous insulin infusion therapy is recommended alongside postoperative continuation for critically ill patients. Prompt resumption of the patient's routine medications post-surgery is also necessary. Conclusions: Optimal glycemic control, both pre-, intra- and perioperatively, correlates with improved outcomes that are comparable to those without diabetes. Targeted efforts are warranted for patients with diabetes undergoing cardiac surgery to ensure long-term benefits for the patients and healthcare systems.