Final answer:
Two hours after drinking a 75-gram glucose solution during a glucose tolerance test, blood glucose levels should be below 140 mg/100 ml to indicate normal glucose metabolism.
Step-by-step explanation:
During a glucose tolerance test, two hours after drinking a glucose solution, ideally, the blood glucose levels should be below 140 mg/100 ml to be considered normal. The test involves fasting blood glucose measurements after 12-14 hours without food, followed by ingestion of a glucose solution (typically 75 grams for an adult), and then measuring blood glucose levels at intervals to assess the body's ability to metabolize glucose. In a person who can tolerate glucose well, the blood sugar level should return to normal 2½ hours post-ingestion. Elevated levels beyond the normal range suggest an impaired glucose tolerance or diabetes mellitus.