In 1957, Clvert found that experimental diabetic animals with pancreas removed and pituitary gland removed were significantly less diabetic and had increased sensitivity to insulin and frequent spontaneous hypoglycemia, called Houssay’s phenomenon. Houssay’s syndrome is also known as “Diabetes Disappearing Syndrome”, which means that in diabetic patients with hypopituitarism, the hyperglycemia of diabetes can be relieved by itself, and the sensitivity to insulin is increased, and even hypoglycemia can occur. After appropriate hormone supplementation, the symptoms of diabetes reappear. In the past, the incidence of this disease was thought to be low, but in recent years, with the increase in the prevalence of diabetes and the increase in life expectancy, the incidence of this disease has a tendency to increase, and many patients are in the subclinical stage, which is not easily detected clinically, and the diagnosis and treatment of Houssay’s syndrome was once neglected. Tumors, infections, postpartum hemorrhage, and autoimmune inflammation of the pituitary gland can all lead to hypopituitarism. In the past, hypopituitarism occurred in women with multiple births, multiple children and postpartum hemorrhage, and the latter caused anterior pituitary hypofunction, also known as Silhan’s syndrome. In recent years, due to the general improvement of medical conditions, the incidence of this disease has been decreasing year by year. In contrast, anterior pituitary hypoplasia caused by pituitary tumors, inflammation, ischemia or immune damage is gradually increasing. In addition, it has been suggested that diabetic microangiopathy is one of the pathogenic mechanisms. Some studies have reported that diabetes mellitus leads to vascular degeneration, microcirculatory disorders and small arteriosclerosis due to disorders of glucose and lipid metabolism, and increased blood viscosity, increased platelet and red blood cell aggregation, resulting in vascular embolism, and in some cases, death due to pituitary infarction. Clinical manifestations When diabetes combined with hypopituitarism, due to the lack of insulin antagonistic glucose-raising hormones such as thyroid hormone, growth hormone, glucocorticoids, etc., in the case of applying insulin or oral hypoglycemic drugs, the sensitivity to drugs is enhanced, and frequent hypoglycemia and even hypoglycemic coma occur, giving doctors and patients a feeling that diabetes is “getting better” or “cured”. This gives doctors and patients the illusion that diabetes is “getting better” or “cured”. Some patients with Houssay’s syndrome also show large fluctuations in blood glucose and even fasting hyperglycemia, probably because these patients are very sensitive to insulin and are prone to symptoms similar to those of brittle diabetes, or even hypoglycemia followed by hyperglycemia. In addition, there may also be manifestations related to anterior pituitary hormone deficiency, such as weakness, poor appetite, drowsiness, constipation, fear of cold and sweating, loss of libido, hair loss, low blood sodium, anemia, etc. Some scholars summarize that the disease has the following characteristics: (1) it is more common in women; (2) it takes longer to diagnose diabetes, and the underdiagnosis rate of anterior hypopituitarism is higher; (3) frequent hypoglycemia or large fluctuations in blood sugar, blood pressure may be low, and after hormone replacement therapy, blood pressure may rise to varying degrees, and even obvious hypertension may appear; (4) hypogonadism appears early and is the most common; followed by secondary hypothyroidism. (5) Loss of pubic and axillary hair is the most common, the outer 1/3 of eyebrow hair is lost or sparse, and tooth loss is serious; (6) Mild hypoproteinemia and mild anemia may be present; (7) Clinical symptoms are weakness, poor appetite, drowsiness, constipation, and cold sweating; (8) Low blood sodium, but normal blood potassium. (9) Prednisone and thyroid tablet replacement therapy can be effective in about 1 to 2 days, and the earliest general condition such as weakness, poor appetite and mental depression can be improved, and blood glucose can be mildly or moderately increased, and the occurrence of hypoglycemia is obviously reduced. Diagnosis Untreated patients or patients with diabetes mellitus for many years should consider this disease when they have automatic remission, reduction or frequent hypoglycemia. If there is a combination of dry and rough skin, fear of cold and sweating, constipation, swelling, thinning and loss of hair, early loss of teeth, weakness, poor appetite, premature amenorrhea and hypogonadism, the combination of anterior pituitary hypofunction should be noted. A detailed history, thorough physical examination, and biochemical tests such as electrolytes can assist in the diagnosis of the disease. The diagnosis can be clarified by measuring the hormone levels of the pituitary-adrenal, pituitary-thyroid and pituitary-gonadal axes. Imaging tests such as pituitary MRI can help to clarify the cause of pituitary lesions. It has been suggested that low blood sodium, low T3 levels and low blood pressure may be more sensitive indicators of combined anterior pituitary hypoplasia in diabetic patients. In elderly patients, lower LH and FSH levels are more sensitive indicators of early hypopituitarism. Treatment If the patient shows pituitary crisis such as hyponatremia, hypoglycemia, hypotension, nausea and vomiting, the patient should be treated with glucose supplementation, fluid replacement and 200-300mg/d of hydrocortisone. Patients with frequent hypoglycemia should be cautiously treated with insulin and drugs with strong hypoglycemic effect, closely monitor blood glucose, add glucocorticoids and thyroid hormones, and adjust them as appropriate after blood glucose rises again. Hormone replacement therapy emphasizes individualized, lifelong treatment, first supplementing glucocorticoids, such as prednisone 5-7.5mg/d. If there are complications such as hyperthermia, infection, surgery, etc., the hormone dose needs to be increased, and hydrocortisone 100-300mg/d can be ordered quietly, and then reduced to the original maintenance dose after the complications are corrected for several days. Glucocorticosteroid therapy can be used to correct thyroid insufficiency at the same time or after glucocorticoid deficiency has improved, such as with thyroxine tablets, starting at 50ug and gradually increasing the dose. Prednisone and thyroid tablet replacement therapy can be effective in about 1 to 2 days after administration, and the earliest general condition such as weakness, poor performance and mental depression can be improved, blood glucose can be mildly or moderately elevated, but more stable, and the occurrence of hypoglycemia is significantly reduced. The majority of patients have increased urine output and reduced swelling after taking hormones. After a certain period of treatment, urea nitrogen and creatinine are reduced to a certain extent, probably because glucocorticoids and thyroid hormones can increase cardiac output and glomerular filtration rate and antagonize the effect of anti-diuretic hormones or increase the sensitivity of diuretics. In Houssay’s syndrome, the hyperglycemic state of diabetes is masked or partially masked by the combination of diabetes mellitus and hypopituitarism, giving the physician the illusion that the diabetes is cured or reduced. Therefore, it is important to have a comprehensive and systematic understanding of the disease and to make a correct and timely diagnosis to provide a more reasonable treatment plan for the patient in order to avoid delaying the disease.