If you are pregnant and your doctor is concerned about your blood sugar level, he or she may order an oral glucose tolerance test. The oral glucose tolerance test is a procedure that is used to determine whether you have gestational diabetes. If you are not pregnant, your doctor may order the test in order to check for Type 2 diabetes. An oral glucose tolerance test examines how your body reacts to glucose.

Preparing for the Oral Glucose Tolerance Test

Your doctor will give you detailed directions telling you what to do to prepare for your test. It's important to eat a regular diet up until eight hours prior to the test. Keep in mind that you are not allowed to eat or drink anything beyond that point. Your doctor should know of any medicines you are taking. You must also tell your doctor about any unusual symptoms you may have, even if they are just typical cold or flu symptoms. This is very important, since illness and some medications can alter your results and cause a misdiagnosis.

What to Expect on the Day of Your Appointment

In order to gain a baseline measurement, your glucose level will be determined once you arrive for your appointment. This is done using a small blood sample from either a finger or vein. You will probably have to remain at the office or laboratory for an extended period of time. This will range from two to three hours after the glucose challenge is administered, depending upon whether you are being checked for gestational diabetes or Type 2 diabetes.

If your doctor is checking for Type 2 diabetes using an oral glucose tolerance test, you will drink 8 ounces of glucose solution. The solution tastes like a very sweet soft drink. Consuming the solution may cause some people to experience nausea or sweating. After two hours, another sample of your blood will be taken, and your glucose level will be measured a second time.

If your doctor is checking for gestational diabetes, you will also drink 8 ounces of glucose solution, but the solution used to screen for gestational diabetes has a higher concentration of glucose in it. It will be very syrupy and sweet, causing you to possibly experience nausea or sweating after you drink it. If you vomit, notify your health care provider. After an hour, a second blood sample will be taken, and your glucose will be measured again. This will be repeated at the two-hour and three-hour marks. After the final glucose test, you can leave the office or laboratory and resume your regular schedule.

What Your Results Mean

An oral glucose tolerance test is less effective at diagnosing Type 2 diabetes than it is at diagnosing gestational diabetes. If two of the glucose tests administered during the procedure are high, you may be diagnosed with gestational diabetes, meaning you will need to take steps to keep your blood sugar levels under control for the remainder of your pregnancy. If you are being screened for Type 2 diabetes, a result that falls in the high range will often prompt your doctor to repeat the test or order others tests be certain that you have type 2 diabetes.