Final answer:
The Oral Glucose Tolerance Test (OGTT) is the main diagnostic method for gestational diabetes mellitus. Upon confirmation of diabetes, further tests such as the Insulin Tolerance Test (ITT) and Glucagon Tolerance Test (GuTT) may be used to specify the type of diabetes. The A1C test also offers a long-term view of blood glucose management.
Step-by-step explanation:
The most common diagnostic method for gestational diabetes mellitus (GDM) is the Oral Glucose Tolerance Test (OGTT). This test involves fasting blood glucose measurement, followed by ingestion of a glucose-rich drink, and subsequent blood glucose measurements at set intervals to assess how well the body processes glucose.
Other tests such as the Insulin Tolerance Test (ITT) and Glucagon Tolerance Test (GuTT) might be used to differentiate the type of diabetes once GDM is confirmed. These tests help in understanding whether the diabetes is insulin dependent or independent by assessing the functioning of the pancreas and its hormone production.
Advanced tests like A1C can also provide insights into the patient's average blood glucose levels over a few months, offering a longer-term perspective on glucose management.