Autonomic neuropathy: clinical and instrumental findings

The development of sensitive techniques evaluating functions under autonomic control has allowed the early detection of widespread abnormalities in diabetes mellitus. However, despite a high frequency of functional abnormalities, an overt clinical syndrome develops slowly and is quite rare. Characteristic clinical features, more recent methods for evaluating autonomic function, diagnostic procedures, and main instrumental findings in a diabetic population are reported. Emphasis is given to more promising techniques evaluating autonomic control of the cardiovascular system, such as myocardial scintigraphy and assessment of 24-h blood pressure and heart rate variability. The clinical meaning of the number of functional abnormalities observed in diabetic patients is considered. While the role of autonomic neuropathy in the pathogenesis of gastrointestinal motor disorders, hypoglycaemia unawareness or diabetic impotence needs to be revised, the importance of autonomic-related sweating and blood flow abnormalities in the pathogenesis of diabetic foot lesions is now better documented. Moreover, growing evidence of the importance of autonomic control of cardiovascular system, together with cardiovascular dysfunction linked to diabetic autonomic neuropathy, supports the hypothesis of a possible role of autonomic neuropathy in the increased cardiovascular morbidity and mortality observed in diabetic patients.