**Core Concept**
Cushing's syndrome is a hormonal disorder caused by prolonged exposure to high levels of cortisol, a steroid hormone produced by the adrenal glands. This excess cortisol can result from various causes, including a pituitary tumor, adrenal tumor, or long-term use of corticosteroid medications.

**Why the Correct Answer is Right**
Cushing's syndrome is characterized by a multitude of symptoms and signs, primarily due to the systemic effects of cortisol. These features include **weight gain**, particularly in the truncal region (central obesity), **moon facies**, **buffalo hump** (dorsocervical fat pad), **purple striae**, **hypertension**, **diabetes mellitus**, **glucose intolerance**, **hirsutism**, **irregular menstrual cycles**, and **osteoporosis**. The correct answer is the option that does not align with these typical manifestations.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is a common feature of Cushing's syndrome, as cortisol excess leads to insulin resistance and glucose intolerance, often resulting in the development of diabetes mellitus.
**Option B:** Hypertension is a frequent finding in Cushing's syndrome due to the mineralocorticoid effects of excess cortisol, which increases sodium retention and blood pressure.
**Option C:** This option is a characteristic feature of Cushing's syndrome, as the excess cortisol disrupts the normal hypothalamic-pituitary-adrenal axis, leading to irregular menstrual cycles and amenorrhea.

**Clinical Pearl / High-Yield Fact**
When suspecting Cushing's syndrome, always remember to look for the "truncal obesity" sign, which is a key feature of the disease. Truncal obesity refers to the accumulation of fat in the upper body, particularly around the abdominal region, which is a hallmark of Cushing's syndrome.

**Correct Answer:** D.