Whether or not blood sugar will be high without breakfast is related to whether or not you have diabetes. If people without diabetes do not eat breakfast, blood sugar is generally in the normal range and will not increase; patients with diabetes do not eat breakfast, blood sugar may be high or low, the specific increase or decrease varies from person to person. 1, the general population: people without diabetes, do not eat breakfast blood sugar is generally not high, usually within the normal range. The general population does not eat breakfast generally does not stimulate insulin secretion, and the body has a lot of glucagon can make blood sugar to maintain a relatively constant state; but if the patient is thin, do not eat may appear hypoglycemia; 2, diabetic patients: diabetic patients do not eat breakfast in the morning, the changes in blood sugar is very complex, do not eat breakfast blood sugar is mainly related to the patient’s insulin secretion level. If the patient’s blood sugar is not well controlled, insulin cannot be secreted as needed, glucagon rises in the morning, and it is possible that blood sugar will rise without breakfast. If a patient has hypoglycemia at night and does not eat breakfast in the morning, blood sugar may also be elevated, and this elevation is caused by reflex hypoglycemia. In addition, some patients use more hypoglycemic drugs, or use appropriate drugs but the patient is more sensitive to drugs, not eating breakfast blood sugar may fall. Therefore, diabetic patients should eat and take medication at regular intervals, so as to ensure that their blood sugar is in a relatively stable state and reduce the emergence of various acute complications.