**Core Concept**
In hypoglycemia, the body attempts to maintain blood glucose levels through the release of various hormones, primarily from the pancreas, adrenal glands, and liver. The glucagon-glucose feedback loop is crucial for correcting hypoglycemia.

**Why the Correct Answer is Right**
Glucagon is released in response to low blood glucose levels, stimulating glycogen breakdown in the liver to release glucose into the bloodstream. Glucagon also inhibits glycogen synthesis and stimulates gluconeogenesis. Glucocorticoids, such as cortisol, are released in response to stress, including hypoglycemia, and promote gluconeogenesis and glycogenolysis. Epinephrine (adrenaline) is released from the adrenal glands in response to hypoglycemia and stimulates glycogenolysis and gluconeogenesis. Insulin, however, is the hormone that decreases in response to hypoglycemia, as it would otherwise promote glucose uptake by cells, exacerbating the condition.

**Why Each Wrong Option is Incorrect**
**Option A:** Glucagon increases in response to hypoglycemia, making it incorrect.
**Option B:** Epinephrine increases in response to hypoglycemia, making it incorrect.
**Option C:** Glucocorticoids increase in response to hypoglycemia, making it incorrect.

**Clinical Pearl / High-Yield Fact**
Remember that insulin levels decrease in response to hypoglycemia, and glucagon levels increase to promote glucose release from the liver.

**Correct Answer: D. Insulin.