Mild elevations of blood glucose after breakfast can be asymptomatic, while severe elevations can lead to associated emergencies, increased risk of infection, and damage to various systems throughout the body. Most mild elevations in blood glucose have no obvious symptoms, but the damage to all parts of the body is subtle. If blood glucose rises sharply, diabetic ketoacidosis, hyperosmolar hyperglycemia syndrome and other critical illnesses can occur. Long-term elevation of blood glucose is also prone to complications of various infections, such as urinary tract infections, skin infections, tuberculosis, etc., which can also lead to an increased risk of cardiovascular and cerebrovascular diseases (e.g., cardiac infarction, stroke, etc.). Diabetic patients are advised to control their blood glucose level reasonably under the guidance of their doctors.