High fasting blood glucose may be caused by diabetes, or it may be caused by infection, stress, etc. High fasting blood glucose needs to be evaluated by a medical professional for standardized treatment. Diabetes mellitus is a group of metabolic diseases characterized by chronic hyperglycemia caused by multiple etiological factors, and is caused by defects in insulin secretion and/or utilization, so high fasting blood glucose may be caused by diabetes mellitus. In addition to diabetes mellitus, high fasting blood glucose may also occur when the organism is infected by pathogenic microorganisms, or when there are stress factors or surgery. It is recommended that patients with high fasting blood sugar go to the hospital in time to avoid delaying their condition.