The causes of abnormal glucose tolerance test are diabetes or pre-diabetes, stress, and diseases secondary to elevated blood glucose. Glucose tolerance test is short for oral glucose tolerance test, patients in fasting, oral glucose after 30min, 1h, 2h blood draw to check the venous plasma glucose, glucose tolerance normal value for fasting glucose <6.1mmol / L and oral glucose 2 hours after glucose glucose <11.1mmol / L. 1. Diabetes mellitus: patients with diabetes mellitus have decreased pancreatic islet function, decreased ability to lower serum glucose, and abnormal glucose tolerance test, which is manifested as fasting blood glucose ≥7.0mmol/L or 2-hour blood glucose after oral glucose ≥11.1mmol/L. If the fasting blood glucose is between 6.1 and 6.9mmol/L or hourly postprandial blood glucose is between 7.8 and 11.1mmol/L, then it is diabetes mellitus. Pre-diabetes. 2. Stress: emotional excitement, short-term strenuous exercise, serious infection, surgery, etc. can cause temporary elevation of blood glucose, causing abnormal glucose tolerance. 3. Diseases with secondary elevation of blood glucose: such as hyperthyroidism, acromegaly, cortisolism and other diseases may cause elevation of blood glucose, resulting in abnormal glucose tolerance test. For patients with abnormal glucose tolerance test, it is necessary to consult a doctor at the endocrinology department of the hospital in time to formulate an appropriate treatment plan.