What is the key rationale for using a 2-hour OGTT in diabetes screening?

• A. It measures fasting glucose only
• B. Glucose metabolism is assessed after 2 hours
• C. It does not require fasting
• D. It detects HbA1c levels

Answer: (B)

The main idea is to test how the body handles a glucose spike over time. In the oral glucose tolerance test, you give a standard glucose amount after fasting and then look at the blood glucose level two hours later to see how well glucose is cleared. That two-hour measurement reflects the combined action of insulin secretion and tissue insulin sensitivity during the post-load period. People can have normal fasting glucose but still have high glucose after loading, which reveals impaired glucose tolerance or diabetes that fasting tests miss. HbA1c measures average glucose over months and doesn’t directly assess the acute post-load response, so the two-hour reading provides unique, valuable information.