Dizziness when hungry may be a low blood sugar reaction, not necessarily caused by diabetes. To determine whether it is diabetes, tests such as glucose tolerance can be performed, and causes such as abnormal thyroid function and heart disease should also be ruled out. In addition to the symptoms of diabetes, such as polyuria, polydipsia, polyphagia, weight loss, etc., some patients may also experience preprandial reactive hypoglycemia, and dizziness and fatigue may occur when they are hungry. The reason for this may be due to impaired glucose tolerance and abnormal insulin function, and tests such as glucose tolerance and glycosylated hemoglobin are needed to determine whether it is due to diabetes. If the glucose tolerance test shows that fasting blood glucose is higher than 7.0mmol/L, or blood glucose 2 hours after meal or random blood glucose is higher than 11.1mmol/L, or glycated hemoglobin is higher than 6.5%, and has the symptom of “three more and one less”, it can be diagnosed as diabetes, and then it is necessary to consider the possibility that fainting when you are hungry is diabetes. If you are hungry, there may be other reasons besides diabetes, so it is recommended that you consult a doctor in time.