Normal blood sugar refers to the levels of glucose (sugar) in the blood that are considered within a healthy range. It is typically defined as a fasting blood sugar level of 70 to 99 milligrams per deciliter (mg/dL) or a postprandial blood sugar level (after eating) of 70 to 140 mg/dL, according to the American Diabetes Association. Maintaining normal blood sugar levels is important for overall health and can help prevent complications associated with diabetes.