Cardiovascular autonomic neuropathy in diabetes: clinical impact, assessment, diagnosis, and management

Cardiovascular Autonomic Neuropathy (CAN) Subcommittee of Toronto Consensus Panel on Diabetic Neuropathy worked to update CAN guidelines, with regard to epidemiology, clinical impact, diagnosis, usefulness of CAN testing, and management. CAN is the impairment of cardiovascular autonomic control in the setting of diabetes after exclusion of other causes. The prevalence of confirmed CAN is around 20%, and increases up to 65% with age and diabetes duration. Established risk factors for CAN are glycaemic control in type 1 and a combination of hypertension, dyslipidemia, obesity and glycaemic control in type 2 diabetes. CAN is a risk marker of mortality and cardiovascular morbidity, and possibly a progression promoter of diabetic nephropathy. Criteria for CAN diagnosis and staging are: 1. one abnormal cardio-vagal test identifies possible or early CAN; 2. at least two abnormal cardio-vagal tests are required for definite or confirmed CAN; and 3. the presence of orthostatic hypotension (OH), in addition to heart rate test abnormalities, identifies severe or advanced CAN. Progressive stages of CAN are associated with increasingly worse prognosis. CAN assessment is relevant in clinical practice for 1. diagnosis of CAN clinical forms, 2. detection and tailored treatment of CAN clinical correlates (e.g. tachycardia, OH, nondipping, QT interval prolongation), 3. risk stratification for diabetic complications and cardiovascular morbidity and mortality, and 4. modulation of targets of diabetes therapy. Evidence on the cost-effectiveness of CAN testing is lacking. Apart from the preventive role of intensive glycaemic control in type 1 diabetes, recommendations cannot be given for most therapeutic approaches to CAN. Copyright © 2011 John Wiley & Sons, Ltd.