What type of specimen should be collected for a glucose tolerance test?

The glucose tolerance test is designed to assess how well the body processes glucose and requires specific preparation to yield accurate results. In this case, a fasting blood specimen is essential because it establishes a baseline level of glucose in the blood before any glucose intake. This fasting period, typically lasting 8 to 12 hours prior to the test, ensures that other influencing factors, such as recent food consumption, do not affect the results.

Collecting a fasting blood specimen allows for a clearer evaluation of the body's response to glucose after it is administered during the test. The test itself involves measuring blood glucose levels at intervals after ingestion of a glucose solution, following the initial fasting measurement. This sequence of controlled measurements is crucial for diagnosing conditions like diabetes or impaired glucose tolerance, making the fasting specimen necessary for accurate interpretation of the test results.