Acceptable blood glucose levels are 100 milligrams of glucose per deciliter after a fasting blood glucose test; less than 140 mg/dL for people 50 years old or younger; less than 150 mg/dL for people 50 to 60; and less than 160 mg/dL for people over 60, states WebMD. Random glucose levels depend on when the patient had his last meal.
Usually, 80 to 120 mg/dL before eating is acceptable, and 100 to140 mg/dL is acceptable at bedtime, notes WebMD. Blood glucose is tested to check if a person has diabetes or pre-diabetes, says WebMD. It is also used to see if a diabetic person is getting the right amount of insulin or if a patient is suffering from low blood sugar, also known as hypoglycemia. Pregnant women also take an oral glucose tolerance test to check for gestational diabetes. Other patients have blood drawn to have their glucose levels checked.
The fasting glucose test requires patients fast for eight hours, says WebMD. This is a test that measures insulin levels. Random glucose tests can be taken several times over the course of a day. In non-diabetics, glucose levels don't change very much over a day, so large variances in blood glucose levels may indicate a problem.