A normal blood sugar level is less than 100 milligrams per deciliter when fasting and 140 milligrams per deciliter two hours after eating a meal. A milligram per deciliter is a unit of measure that shows the concentration of a substance in a specific amount of fluid.
Having consistently high levels of blood sugar, or glucose, sometimes causes harm to the body over time and leads to health problems commonly associated with diabetes. WebMD suggests that following a diet and exercise program often halts the progression of high blood sugar levels, commonly known as prediabetes, into full diabetes. Blood sugar levels of 200 or higher with symptoms of increased urination, thirst and weight loss are signs of diabetes.