The glucose tolerance test is used to investigate the control of glucose in the human body - HSC - SSCE Biology - Question 12 - 2019 - Paper 1

To determine which graph best represents the glucose tolerance tests, we first understand the expected results in both non-diabetic and Type 2 diabetic individuals.

1. Non-diabetic Response: In a non-diabetic person, after the consumption of glucose, the blood glucose levels spike quickly, reaching a peak usually around 30 minutes, and then decline back to normal levels within 120 minutes.

2. Type 2 Diabetic Response: In contrast, a person with untreated Type 2 diabetes will exhibit a prolonged spike in blood glucose levels. The levels may remain elevated significantly longer than in a non-diabetic individual, showing a less efficient response to glucose.

Upon analyzing the graphs:

• Graph A: Shows a quick return to baseline for non-diabetics but does not illustrate prolonged high levels for Type 2.
• Graph B: Similar to A, it does not represent a significant elevation for the diabetic individual.
• Graph C: Indicates a moderate peak but still lacks the prolonged elevation expected.
• Graph D: Clearly shows a sharp increase in blood glucose at 30 minutes with a plateau at higher levels for the diabetic individual, which is characteristic of Type 2 diabetes, while the non-diabetic values return to normal levels.

Hence, Graph D accurately represents the results of glucose tolerance tests in both groups.