The enigma of autonomic failure in diabetes.

The extent of autonomic failure in diabetes and the damage that results both in terms of structure and function is seldom realised. This article focuses on the consequences of autonomic denervation of several different forms of smooth muscle, notably those of arterial wall, vas deferens, stomach, iris and bronchial wall. The clinical implications of these changes are described, in particular the problems arising from vascular (and vas deferens) calcification and abnormalities of vascular reactivity; insulin-induced postural hypotension and the splanchnic circulation; the anaemia of autonomic neuropathy from failure of erythropoietin production; gastromyopathy as a cause of gastroparesis; iritis as a symptom related to diabetic autonomic neuropathy (DAN); the concept of an autoimmune basis for DAN; and failure of bronchial reactivity and respiratory arrests in DAN. The importance of clinical observation leading to clinical experiment and research, together with the stimulation of ideas by collaboration with clinical colleagues in other disciplines is emphasised throughout.