Though not routinely used anymore, the oral glucose tolerance test (OGTT) is the gold standard for making the diagnosis of type 2 diabetes. However, it is still commonly used for diagnosing gestational diabetes.
With an oral glucose tolerance test, the person fasts overnight (at least eight but not more than 16 hours). Then, the fasting plasma glucose is tested. After this test, the person receives 75 grams of glucose (100 grams for pregnant women). There are several methods used by obstetricians to do this test, but the one described here is standard. Usually, the glucose is in a sweet-tasting liquid that the person drinks. Blood samples are taken up to four times to measure the blood glucose.
The Diabetes Prevention Program (DPP) was a major clinical trial, or research study, aimed at discovering whether either diet and exercise or the oral diabetes drug metformin (Glucophage) could prevent or delay the onset of type 2 diabetes in people with impaired glucose tolerance (IGT).
The answer is yes. In fact, the DPP found that over the three years of the study, diet and exercise sharply reduced the chances that a person with IGT would develop diabetes. Metformin also reduced risk, although...
For the glucose tolerance test to give reliable results, the person must be in good health (not have any other illnesses, not even a cold). Also, the person should be normally active (not lying down, for example, as an inpatient in a hospital) and should not be taking drugs that could affect the blood glucose. For three days before the test, the person should not eat a diet high in carbohydrates (150- 200 grams per day). The morning of the test, the person should not smoke or drink coffee.
What does the glucose tolerance test measure?
The classic oral glucose tolerance test measures blood glucose levels five times over a period of three hours. Some doctors simply get a beginning blood sample followed by a sample two hours after drinking the glucose solution. In a person without diabetes, the glucose levels rise and then fall quickly. In someone with diabetes, glucose levels rise higher than normal and fail to come back down as fast.
People with glucose levels between normal and diabetic have impaired glucose tolerance (IGT). People with IGT do not have diabetes. Each year, 1%-5% of people whose test results show IGT actually develop diabetes. Weight loss and exercise may help people with IGT return their glucose levels to normal. In addition, some doctors advocate the use of medications, such as metformin (Glucophage), to help prevent or delay the onset of overt diabetes. Recent studies have shown that IGT itself may be a risk factor for the development of heart disease, and whether IGT turns out to be an entity that deserves treatment itself is something that is currently debated.
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People who experience hypoglycemia several times in a week should call their health care provider. It's important to monitor your levels each day so you can make sure your numbers are within the range. If you are pregnant always consult with your health care provider.
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However, it's important to continue to track your numbers so that you can make lifestyle changes if needed. If you are pregnant always consult with your physician.
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Even if your number is high, it's not too late for you to take control of your health and lower your blood sugar.
One of the first steps is to monitor your levels each day. If you are pregnant always consult with your physician.
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