After meals, a normal blood sugar level should be less than 180 milligrams per deciliter, according to MedlinePlus. A person should test blood sugar levels from one to two hours following a meal, and a normal level is the same for both Type 1 and Type 2 diabetes.
Most people who have diabetes check blood sugar before meals and at bedtime, explains MedlinePlus. It is also important to check blood sugar if feeling ill, before and after exercise and if under stress. It helps to keep track of blood sugar numbers, diet, time of day and exercise habits. If blood sugar is too high without a reason for more than a couple of days, it is necessary to contact a doctor.