A normal range for fasting blood sugar is less than or equal to 100 milligrams per deciliter; for postprandial blood sugar it is less than 140 milligrams per deciliter for people younger than 50, states WebMD. For people 50 to 60, under 150 milligrams per deciliter is in normal range.
For people age 60 and above, the normal postprandial blood sugar range is less than 160 milligrams per deciliter as of 2015. Doctors give the two-hour postprandial blood sugar test to determine whether a diabetic patient is taking the correct amount of insulin with meals, not as a diabetes diagnostic test. The test gauges the patient's blood glucose level precisely two hours after the patient begins eating a meal, notes WebMD. The fasting blood sugar test, usually the first diabetes test, measures a patient's blood glucose level when the patient has not eaten for eight hours or more.