**Core Concept**
The question is testing the effects of various hormones on glucose metabolism, specifically their ability to cause hyperglycemia. The correct answer should be a hormone that directly increases glucose levels in the blood without affecting glycogen synthesis or gluconeogenesis.

**Why the Correct Answer is Right**
The hormone glucagon-like peptide-1 (GLP-1) can cause hyperglycemia by stimulating the release of insulin from pancreatic beta cells. However, this effect is indirect and occurs through the activation of GLP-1 receptors on these cells. GLP-1 has no known effects on glycogen synthesis or gluconeogenesis, making it a suitable answer. GLP-1 works by binding to its receptor, which activates adenylate cyclase and increases intracellular cyclic AMP (cAMP) levels. Elevated cAMP activates protein kinase A (PKA), which in turn phosphorylates and activates the insulin receptor substrate (IRS), leading to insulin release.

**Why Each Wrong Option is Incorrect**
**Option A:** Glucagon is a hormone that directly stimulates glycogen breakdown (glycogenolysis) and gluconeogenesis, making it an incorrect answer.
**Option B:** Insulin is a hormone that decreases glucose levels in the blood by facilitating glucose uptake in cells and inhibiting glycogenolysis and gluconeogenesis, making it an incorrect answer.
**Option C:** Growth hormone can cause hyperglycemia by stimulating gluconeogenesis and glycogenolysis, making it an incorrect answer.

**Clinical Pearl / High-Yield Fact**
The GLP-1 receptor agonists, such as exenatide and liraglutide, are used as antidiabetic medications that work by mimicking the effects of GLP-1 and stimulating insulin release from pancreatic beta cells.

**Correct Answer: D. GLP-1**