Circulation in Lower Extremities and Sympathetic Function in Diabetic Patients: Significance of Age

Circulation in the lower extremities and sympathetic function have been studied extensively in long-term type I (insulin-dependent) diabetic patients. Arterial lesions are demonstrable in these patients, but clinical vascular disease (e.g., ischemic gangrene) manifests itself mainly in elderly diabetic patients, suggesting important interactions between vascular effects of aging and diabetes mellitus. Sympathetic denervation reduces spontaneous variability in resting blood flow in the foot. This abnormality impairs thermoregulation and contributes to the development of orthostatic hypotension in diabetic patients. Cardiovascular function may already be impaired in the elderly due to a reduced cardiovascular responsiveness to catecholamines. The addition of sympathetic denervation may further decrease sympathetic function in the elderly. Impaired vasomotor control and hypotension due to autonomic dysfunction can potentially magnify perfusion problems due to vascular disease, thereby increasing the risk of clinically significant ischemia.