Hypoglycemia secondary to endocrine deficiencies is uncommon, but it occurs. The endocrine deficiency may be of hypothalamic-pituitary origin or may be due to primary failure of the adrenal gland or the thyroid gland. If hypoglycemia is suspected, the diagnosis should be established immediately by measurement of the blood sugar level. Blood should also be obtained for subsequent use in confirming the diagnosis of the endocrine disease responsible for causing the hypoglycemia. A 50% dextrose in water solution should immediately be injected, and fluid therapy consisting of 5% dextrose in normal saline should be initiated. Intravenous cortisone should be given if primary or secondary adrenal cortical insufficiency is suspected until the results of the biochemical tests become available. If hypothyroidism is suspected, intravenous L-thyroxine should be given carefully in addition to the cortisone treatment. Failure in recognizing hormone deficiencies as the cause of hypoglycemia in some patients and failure in promptly correcting the condition may lead to fatal consequences.