**Question:** After 50 gm of glucose of feed orally

**Core Concept:** Glucose tolerance test (GTT) and its interpretation

**Why the Correct Answer is Right:**
A glucose tolerance test (GTT) is a diagnostic test used to evaluate an individual's glucose homeostasis and to screen for diabetes mellitus. In this test, a glucose load is administered, and blood glucose levels are measured at different time points to assess the body's response to the glucose challenge. The most common glucose load used in the GTT is a solution containing 75 g of glucose dissolved in water. When 50 g of glucose is given orally, it is usually done to evaluate glucose tolerance in patients with suspected impaired glucose tolerance or diabetes mellitus, where the oral glucose tolerance test is used as a substitute for the standard 75 g GTT.

**Why Each Wrong Option is Incorrect:**
A. **Option A:** This answer choice refers to the standard 75 g GTT, which is not applicable for the oral glucose tolerance test using 50 g of glucose.
B. **Option B:** This answer choice does not address the correct use of the oral glucose tolerance test with 50 g of glucose.
C. **Option C:** The oral glucose tolerance test using 50 g of glucose is not just for screening purposes, but also helps in diagnosing impaired glucose tolerance and diabetes mellitus.
D. **Option D:** This answer choice discusses the 75 g GTT, not the appropriate oral glucose tolerance test for 50 g of glucose.

**Correct Answer:** **Option D:** The oral glucose tolerance test using 50 g of glucose is a valid test for evaluating glucose tolerance and diagnosing impaired glucose tolerance and diabetes mellitus in patients with suspected impaired glucose tolerance or diabetes mellitus. This test is practical and easy to perform, making it a suitable option for screening and diagnosis.

**Clinical Pearls:**
1. The oral glucose tolerance test using 50 g of glucose is a practical alternative to the standard 75 g GTT, particularly in resource-limited settings.
2. The test is used to evaluate glucose tolerance and diagnose impaired glucose tolerance and diabetes mellitus in patients with suspected impaired glucose tolerance or diabetes mellitus.
3. The interpretation of the oral glucose tolerance test using 50 g of glucose requires understanding of the glucose tolerance curve, including fasting, 1 hour, 2 hours, and 3 hours postprandial glucose levels.
4. The oral glucose tolerance test can be used to diagnose impaired glucose tolerance and diabetes mellitus based on World Health Organization (WHO) criteria:

* Fasting blood glucose level: ≥ 6.1 mmol/L (110 mg/dL)
* 1 hour postprandial glucose level: ≥ 11.1 mmol/L (200 mg/dL)
* 2 hours postprandial glucose level: ≥ 11.1 mmol/L (200 mg/dL)
* 3 hours postprandial glucose level: ≥ 11.1 mmol/L (200 mg/dL)

**Explanation:**

The oral glucose tolerance test