What is the normal range for serum glucose levels?

The normal result for a blood glucose test is a value between 70 and 100 milligrams per deciliter, states the U.S. National Library of Medicine. This is the normal value for a fasting test, meaning that the patient has not eaten in eight hours.

A physician may order a blood glucose test if the patient is diabetic, at risk for diabetes or has an increase in urination, blurred vision, confusion or certain behavioral changes, fainting spells, and seizures, according to the U.S. National Library of Medicine. The test helps a physician diagnose certain conditions such as pancreatitis or an overactive thyroid gland.