**Core Concept**
Insulin is a hormone secreted by the beta cells of the pancreas, playing a crucial role in glucose metabolism. It facilitates the uptake of glucose by cells, thereby lowering blood glucose levels.

**Why the Correct Answer is Right**
Insulin exerts its effects by binding to insulin receptors on the surface of target cells, triggering a cascade of intracellular signaling events that ultimately lead to the translocation of glucose transporter type 4 (GLUT4) to the cell surface. This process is mediated by the insulin receptor substrate (IRS) proteins, which activate phosphatidylinositol 3-kinase (PI3K), leading to the activation of protein kinase B (Akt). The activated Akt then phosphorylates and inhibits the enzyme glycogen synthase kinase 3 (GSK-3), allowing for the increased synthesis of glycogen and the uptake of glucose.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, but we can discuss a general approach to evaluating the options. Typically, options would list specific effects of increased insulin, such as increased glucose uptake, glycogen synthesis, or inhibition of gluconeogenesis.
* **Option B:** This option might be incorrect if it describes a consequence of insulin deficiency, such as increased glucose production in the liver.
* **Option C:** This option might be incorrect if it describes a mechanism of action that is not directly related to insulin signaling, such as the activation of adenylyl cyclase.

**Clinical Pearl / High-Yield Fact**
One key clinical implication of insulin resistance is the development of type 2 diabetes, a condition characterized by impaired glucose uptake and increased glucose production in the liver.

**Correct Answer: D.**