**Core Concept**
Hypoglycemia is a state of abnormally low blood glucose levels, which triggers a complex physiological response to raise blood glucose levels. This involves the release of various hormones, including insulin, glucagon, and epinephrine, among others.

**Why the Correct Answer is Right**
During hypoglycemia, the body initially attempts to increase glucose levels through the release of glucagon and epinephrine. Glucagon stimulates glycogen breakdown in the liver, releasing glucose into the bloodstream, while epinephrine promotes the breakdown of glycogen and fat for energy. However, insulin, which is released in response to elevated blood glucose levels, actually works to decrease blood glucose levels by facilitating glucose uptake in cells. As such, insulin levels do not increase in response to hypoglycemia, as this would counteract the body's efforts to raise blood glucose levels.

**Why Each Wrong Option is Incorrect**
**Option A:** Glucagon is released in response to hypoglycemia, stimulating glycogen breakdown and glucose release into the bloodstream.
**Option B:** Epinephrine is released in response to hypoglycemia, promoting the breakdown of glycogen and fat for energy.
**Option C:** Glucose-dependent insulinotropic polypeptide (GIP) and gastric inhibitory polypeptide (GIP) are released in response to hypoglycemia, also promoting glucose uptake in cells.

**Clinical Pearl / High-Yield Fact**
In managing hypoglycemia, it is essential to recognize that insulin therapy can worsen hypoglycemia, as it promotes glucose uptake in cells. In patients with diabetes, it is crucial to use glucagon or other glucose-raising agents to counteract hypoglycemia.

**Correct Answer: D. Insulin**