Diabetic patients may have elevated fasting blood glucose in the morning and normal postprandial blood glucose. The causes of elevated fasting blood glucose in the morning are mainly the following two situations: First, the patient has unnoticeable hypoglycemia during sleep at night, and the body has a protective mechanism after hypoglycemia, which causes a rebound increase in blood glucose, under the influence of which fasting blood glucose will rise significantly. Second, the “dawn phenomenon” occurs, and the secretion of hormones that antagonize insulin, such as growth hormone, cortisol hormone and adrenal hormone, increases significantly after waking up in the morning. This leads to a significant increase in fasting blood glucose. After fasting blood glucose rises, patients need to monitor nighttime blood glucose to rule out any hypoglycemia at night, if not, they can adjust their nighttime treatment plan, such as increasing the amount of insulin before bedtime, which can help reduce fasting blood glucose.