Experiments indicating the presence of an anti-insulin substance in the blood of patients with schizophrenia have been presented by Meduna, Gerty and Urse.1 These authors had observed that schizophrenic patients showed a decreased tolerance to intravenously administered dextrose, and therefore they attempted to determine whether this phenomenon was due to inhibition of insulin. They followed the blood sugar response to 1 unit of insulin in fasting rabbits which were given blood of schizophrenic patients intraperitoneally one hour before the injection of insulin and compared it with the response to the same dose of insulin after injection of normal blood. It was found that the average degree of insulin hypoglycemia in the rabbits treated with blood of schizophrenic patients was less marked than that in the rabbits treated with blood of normal persons. From this they concluded that the blood of schizophrenic patients was characterized by the presence of an