Final answer:
The glucose tolerance test (GTT) is typically used to diagnose type 2 or gestational diabetes by measuring blood glucose levels after a patient consumes a sugary drink following a fasting period. Further tests like ITT or GuTT may be performed to determine the specific type of diabetes if the GTT indicates hyperglycemia.
Step-by-step explanation:
Diagnosing Diabetes Mellitus with the Glucose Tolerance Test
The glucose tolerance test (GTT) is the test most commonly performed to diagnose type 2 or gestational diabetes. GTT is crucial for patients suspected of having diabetes mellitus who do not exhibit glucosuria or have fasting blood glucose levels that are around normal values. The test involves measuring blood glucose after the patient has fasted and then again after consuming a sugary drink, which challenges the body's insulin response mechanism.
If the GTT results indicate hyperglycemia, it suggests a diabetes mellitus diagnosis, and further tests are necessary to determine whether it is insulin dependent or independent. These may include the Insulin Tolerance Test (ITT) and the Glucagon Tolerance Test (GuTT). The ITT can reveal hypoglycemia in Insulin Dependent Diabetes Mellitus cases, while the GuTT can diagnose defective insulin receptors or an excessive presence of insulin antagonists.
For long-term monitoring, the A1C test is utilized as it provides an average blood glucose level over the preceding two to three months. In managing diabetes, endocrinologists may also prescribe lifestyle changes, oral medication, or insulin therapy depending on the type and severity of the condition.