[Human insulin and hypoglycemia]

It has been reported over the last few years that transferring diabetic patients from animal to human insulin can lead, in some of the patients, to a diminution of the classical hypoglycaemic symptoms, as hunger and sweating, and to the more frequent occurrence of neuroglycopenic symptoms, as the first manifestation of hypoglycaemia. These changes seem to involve a fraction of patients estimated between 8 and 36%, depending on the type of selection of the patients. A decrease in the adrenergic counterregulatory response to hypoglycaemia has also been shown in some studies with human insulin. Similar changes in the sequence of hypoglycaemic symptoms are also described in various clinical conditions--as intensive insulin therapy with tight glycaemic control, long diabetes duration and presence of autonomic neuropathy, thus acting as confounding factors. According to these facts, a few recommendations are proposed: briefly, human insulin should only be prescribed to new patients who are able to learn from the very beginning the sequence of hypoglycaemic symptoms with human insulin; patients already treated with porcine insulin should not be transferred to human insulin. On the whole, studies available to date have not shown an increased frequency of severe hypoglycaemia with human insulin; however, this important matter still has to be conclusively clarified through well-designed prospective studies.