A glucose tolerance test measures the ability of a patient to process glucose in their diet. It is simple in concept but requires a strict protocol in order to give useful results.
- The patient's blood sugar level is measured prior to the test;
- The patient is then given a fixed amount of glucose solution to drink;
- The patient's blood is drawn at regular intervals thereafter and the blood sugar is measured at each point. The patient will not be allowed any further food until the protocol is completed.
In a normal patient, the blood sugar does not change very much at all during this time, or goes up slightly after drinking solution only to return to the original number prior to the test.
In a patient with diabetes mellitus, the blood sugar level will go up quickly until it peaks, at which point it will only go down very slowly as the patient urinates.
In a patient with hypoglycemia, the blood sugar level will rise quite quickly, before returning quickly to a low level. This is virtually the only test that will confirm a diagnosis of hypoglycemia as there is no other condition which will cause this result.
The test is not without risk. In a diabetic patient, the blood sugar level could rise to dangerous levels.
In Que Será Será, the patient refused to take this test on the basis that he felt his condition was not related to his weight.