**Core Concept**
The question is testing the student's knowledge of antidiabetic drugs that act independently of insulin. This involves understanding the various mechanisms through which these drugs lower blood glucose levels. The focus is on insulin-independent action, which means these drugs do not stimulate insulin release or use insulin as a mediator.

**Why the Correct Answer is Right**
Metformin is an example of an antidiabetic drug that acts independently of insulin. It works by reducing hepatic glucose production through the inhibition of gluconeogenesis. This process involves the inhibition of key enzymes such as glucose-6-phosphatase and fructose-1,6-bisphosphatase. By decreasing glucose production in the liver, metformin lowers blood glucose levels without directly stimulating insulin release or using insulin as a mediator.

**Why Each Wrong Option is Incorrect**
**Option A:** Sulfonylureas stimulate insulin release from the pancreatic beta cells, making them insulin-dependent. They bind to the sulfonylurea receptor on the beta cells, leading to the closure of potassium channels and an increase in insulin release.

**Option B:** Thiazolidinediones (TZDs) improve insulin sensitivity by activating peroxisome proliferator-activated receptor gamma (PPAR-γ). They work in conjunction with insulin, making them insulin-dependent.

**Option C:** Meglitinides, like nateglinide and repaglinide, also stimulate insulin release from the pancreatic beta cells. They work by closing ATP-sensitive potassium channels, leading to depolarization and insulin release.

**Clinical Pearl / High-Yield Fact**
Metformin is the first-line treatment for type 2 diabetes due to its effectiveness in reducing hepatic glucose production and its relatively low risk of hypoglycemia. It is also known for its gastrointestinal side effects, which can be managed with gradual dose escalation.

**Correct Answer: C. Meglitinides are insulin-independent and work by stimulating insulin release from the pancreatic beta cells.