Diagnosis of diabetic cardiac autonomic neuropathy

Cardiac autonomic neuropathy (CAN) is a common complication in type 1 and 2 diabetes and is defined as the impairment of autonomic control of the cardiovascular system. CAN is strongly associated with increased mortality, and in some studies with morbidity of vascular complications, such as stroke, coronary artery disease and myocardial infarction. At the early stages, CAN can be subclinical and it becomes clinically evident as the disease progresses. Subclinically, the disease is defined by cardiovascular reflex testing, which may have prognostic implications. Clinically, the impairment in autonomic function is associated with resting tachycardia, exercise intolerance, orthostatic hypotension, syncope, intraoperative cardiovascular instability, silent myocardial infarction and ischemia, and increased mortality. Although very common and serious, CAN is a frequently overlooked complication of diabetes. Because the progression of cardiovascular denervation is partly reversible or can be slowed down in the early stages of the disease, recent guidelines strongly recommend screening for CAN in patients with diabetes. In this review we summarize the diagnostic tools suggested in the screening for diabetic CAN.