Cardiac autonomic neuropathy is an underestimated complication among diabetic patients. It affects both the sympathetic and parasympathetic systems and is often associated with other, autonomic or not, complications, which make the patient even more frail. Some autonomic clinical manifestations have a direct impact on perioperative morbidity and mortality. The most important ones consist in haemodynamic instability, rhythmic disorders, mainly related to increased QT interval, and finally a higher risk of cardiorespiratory arrest. Recommendations are proposed before, during and after surgery to reduce the incidence of these complications in high risk patients. A screening for autonomic neuropathy may be helpful to improve the management of patients with diabetes who undergo surgery requiring general anaesthesia.