Sexual impotence with inability to produce erection is a frequent accompaniment of diabetes. Only exceptionally however is impotence complained of as a symptom. Though in no direct sense a danger to the patient's life, impotence is sometimes a source of major distress and, in a few exceptional cases, may lead to suicide. It is therefore important to distinguish the different mechanisms underlying impotence, and in particular to differentiate psychogenic mechanisms, far more relevant than formerly thought in diabetic patients, from organic mechanisms, in particular neuropathic and vascular, uncommonly, endocrine. Besides cases of unequivocal diabetes, there is an abnormally high proportion of patients suffering from "psychogenic" impotence affecting erection who have impaired glucose tolerance. In such patients the disordered metabolism could reflect at neuroendocrine level the existence of neuro-psychological dysfunction, either a cause or a consequence of the impotence. A second possibility is that the metabolic disorder directly impairs neurological function, resulting in neuropathic impotence. Clearer understanding of the complex mechanisms relating disturbance of carbohydrate metabolism to sexual impotence requires multidisciplinary approaches. Such arrangements are necessary for the planning and conduct of schemes of treatment involving to varying extents the special approaches of psychology, sexology, endocrinology, urology and vascular surgery. The success of such treatment will depend largely upon the quality of the diagnostic and therapeutic approach which requires individualised planning.