**Core Concept**
The oral glucose tolerance test (OGTT) is a diagnostic tool used to assess the body's ability to regulate blood glucose levels after consuming a sugary beverage. In children, the test is used to diagnose and manage conditions such as diabetes mellitus and impaired glucose tolerance.

**Why the Correct Answer is Right**
In children, the OGTT involves the administration of a smaller dose of glucose compared to adults, typically 1.75 grams per kilogram of body weight, up to a maximum of 75 grams. This is because children have a higher metabolic rate and are more sensitive to glucose. The test measures the body's ability to regulate blood glucose levels over a period of 2 hours, providing valuable information about insulin sensitivity and glucose metabolism.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the dose of glucose used in the OGTT for children is not a fixed value, but rather a calculated value based on body weight.
**Option B:** This option is incorrect because the OGTT is not typically used to diagnose hypoglycemia, but rather to diagnose hyperglycemia and impaired glucose tolerance.
**Option C:** This option is incorrect because the OGTT is not a diagnostic tool for gestational diabetes, but rather a diagnostic tool for diabetes mellitus in children.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the OGTT should only be performed in children with a fasting glucose level below 126 mg/dL, as a high fasting glucose level may indicate the presence of diabetes mellitus.

**Correct Answer: D. 1.75 grams per kilogram of body weight, up to a maximum of 75 grams.**