In such patients, hypoglycemia is usually a manifestation of pancreatic islet cell tumors producing insulin, primary or secondary adrenal insufficiency, advanced liver disease, pheochromocytoma, IGF-1 secreting tumors, hypothyroidism, substances interfering with insulin and insulin receptor mediated metabolism [non-islet cell tumor hypoglycemia (NICTH)] or antibodies interfering with insulin receptors [2]. The gene discussed is INSR; the disease is hypothyroidism.