If your doctor suspects you have diabetes or pre-diabetes, she will likely order a glucose test. This test measures the amount of sugar, or glucose, in your blood. Your doctor also may order a glucose tolerance test. This measures how well your body metabolizes glucose. The glucose tolerance test also is used to screen for gestational diabetes during pregnancy. The tolerance test often is given the morning because you cannot eat or drink for 12 hours prior to the test, whereas the other type of glucose test may be given at any time of the day.
Regular Glucose Test
The results for your test are measured in milligrams per deciliter of blood, or mg/dL. If you are in the level one category, meaning the "normal" category, you will have a blood-glucose level of up to 100 mg/dL, according to the New York Times. You may have pre-diabetes if your levels are between 100 and 126 mg/dL. If your levels are higher than 126 mg/dL you are likely to be diagnosed with diabetes. This test may be done after fasting or at random. If your test is done at random, your results will depend on your activity level and what you eat or drink prior to the test, note the experts at the National Institutes of Health.
Gestational Diabetes Test
If you are being tested for gestational diabetes, your blood will be tested in one-hour intervals after drinking a solution that contains 3.5 oz sugar. If you fall into the normal range, your blood-glucose levels will be 180 mg/dL or less after one hour. After two hours, they must be lower than 155 mg/dL to fall into this category. Blood-glucose levels that are lower than 140 mg/dL at the three-hour mark are considered normal, according to the Mayo Clinic.
Glucose Tolerance Test
If you are being tested for diabetes specifically, your doctor may order a glucose tolerance test, notes the Mayo Clinic. With this test, you fast and then drink a sugar solution with 2.6 oz sugar. Your blood glucose levels are measured two hours later. If you are in the first, or "normal," category, your blood glucose level will be lower than 140 mg/dL, according to the Mayo Clinic. If you are between 140 mg/dL and 199 mg/dL, you may have pre-diabetes. A level of 200 mg/dL or higher may mean you have diabetes already.
If you take a glucose tolerance test, your doctor may also measure your blood levels at the one-hour mark. If your blood-glucose levels are less than 200 mg/dL at the one-hour mark, you are in the normal category, according to Merck.
