Fasting blood glucose levels should range from 70 mg/dL to 100 mg/dL, according to the American Diabetes Association. Fasting levels are those measured when an individual has not consumed any meals in the eight hours prior to the test.
Postprandial glucose levels are those observed one to two hours after a meal is consumed and should be less than 180 mg/dL.
'Hypoglycemia' refers to lower than optimal levels, while 'hyperglycemia' is the presence of too much sugar in the bloodstream, treated with insulin in diabetics.
Doctors often use an A1C blood test -reflecting the average blood glucose levels over the previous three months- to diagnose type 1 and type 2 diabetes and gauge treatment plans.