In which condition would you expect hyperglycemia to occur?

Hyperglycemia is commonly associated with Cushing's syndrome due to the effects of elevated cortisol levels on glucose metabolism. Cushing's syndrome is characterized by excessive production of cortisol, which can be caused by a variety of factors such as tumors of the adrenal glands or pituitary gland.

Cortisol plays a significant role in gluconeogenesis, the process by which the liver produces glucose from non-carbohydrate sources, and it promotes insulin resistance in peripheral tissues. This combination leads to increased blood glucose levels, resulting in hyperglycemia. Additionally, prolonged elevations in cortisol can disrupt the normal balance of insulin secretion, further contributing to increased glucose levels in the bloodstream.

In contrast, Addison's disease leads to adrenal insufficiency, which typically results in lower levels of cortisol and consequently may cause hypoglycemia rather than hyperglycemia. Graves' disease is primarily associated with hyperthyroidism, where metabolic processes can cause increased energy expenditure but not necessarily hyperglycemia. Pheochromocytoma may lead to episodic hyperglycemia due to catecholamine surges, but it is not as directly linked to chronic hyperglycemia as Cushing's syndrome is.