Blood sugar, also known as glucose, is the main sugar in your blood and your body’s main source of energy. Blood sugars vary all day. A normal fasting blood sugar (before you eat or drink in the morning) is less than 100 mg/dl. Blood sugars anytime of day regardless of when or what the last meal was should always be under 200 mg/dl. Blood sugars exceeding these two levels could signal prediabetes or Type 1 diabetes or Type 2 diabetes. Diabetes is a condition where the body cannot produce enough insulin or use insulin properly to correct blood sugars to safe levels.