The neurologist so frequently is confronted with diagnostic problems involving bizarre nervous symptoms that he should acquaint himself with syndromes which may have as a predominating symptom some nervous manifestation, although the underlying disease may be outside his special field. Hyperinsulinism and hypoglycemia are conditions of this type, and, although not primarily of neurologic importance, the presenting symptoms may be of a distinctly nervous character. Symptoms from both overactivity and underactivity of the endocrine glands generally have been recognized. Thus both exophthalmic goiter and myxedema have been attributed to the thyroid gland for many years. For some unknown reason, however, the recognition of symptoms resulting from the overactivity of certain glands has lagged behind the recognition of the symptoms of underactivity. Diabetes, parathyroid tetany and hyposuprarenalism (Addison's disease) were described long before hyperinsulinism, hyperparathyroidism and hypersuprarenalism. We are limiting this paper to conditions that are the antithesis of diabetes, in