**Core Concept**
Pioglitazone is a thiazolidinedione (TZD) that acts as an agonist at peroxisome proliferator-activated receptor gamma (PPAR-γ) receptors. Activation of PPAR-γ receptors influences the expression of genes involved in glucose and lipid metabolism.

**Why the Correct Answer is Right**
Pioglitazone increases insulin sensitivity by activating PPAR-γ receptors in the adipose tissue and skeletal muscle, thereby reducing insulin resistance. This action decreases glucose production in the liver and increases glucose uptake in peripheral tissues. Additionally, pioglitazone has anti-inflammatory and anti-atherogenic properties, which contribute to its cardiovascular benefits.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because pioglitazone does not significantly affect glucose levels in the absence of insulin.
**Option B:** Incorrect because pioglitazone is not a sulfonylurea, which acts by stimulating insulin release from the pancreas.
**Option C:** Incorrect because pioglitazone does not directly stimulate insulin release from the pancreas; its primary action is to increase insulin sensitivity.

**Clinical Pearl / High-Yield Fact**
Pioglitazone is contraindicated in patients with New York Heart Association (NYHA) class III or IV heart failure due to its potential to exacerbate fluid retention and worsening heart failure.

**Correct Answer:** B.