Final answer:
A glucose tolerance test (GTT) requires a fasting patient and helps to diagnose diabetes mellitus by measuring blood glucose levels before and after glucose ingestion. A steep, sustained rise in blood glucose indicates diabetes. Further tests, like ITT and GuTT, can determine diabetes type and treatment.
Step-by-step explanation:
The glucose tolerance test (GTT) is a diagnostic procedure primarily used for detecting diabetes mellitus. During this test, blood will be drawn from a fasting patient who has followed a carbohydrate-rich diet for three days prior to the test. Initially, fasting blood glucose levels are measured (12-14 hours fasting). The patient is then given an oral dose of glucose, and subsequent blood glucose measurements are taken at regular intervals to assess how well their body processes glucose.
In a GTT, if the patient's blood glucose levels rise steeply and remain elevated beyond 2½ hours after ingesting glucose, this indicates a poor glucose tolerance, typical of diabetes mellitus patients. On the other hand, a normal glucose tolerance is illustrated by blood glucose peaking at about one hour and returning to baseline after about 2½ hours. Further investigation through an Insulin Tolerance Test (ITT) or Glucagon Tolerance Test (GuTT) may be required to determine the type of diabetes and the appropriate treatment protocol.