**Core Concept**
Biguanides are a class of oral antidiabetic drugs that work by inhibiting hepatic gluconeogenesis, thereby reducing blood glucose levels. They are primarily used in the management of type 2 diabetes mellitus.

**Why the Correct Answer is Right**
Biguanides, such as metformin, act by inhibiting the enzyme complex mitochondrial glycerophosphate dehydrogenase (GPDH) in the liver. This inhibition reduces the production of glucose via gluconeogenesis, leading to a decrease in blood glucose levels. As a result, biguanides do not stimulate insulin release but rather decrease glucose production in the liver.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as biguanides do not directly stimulate insulin release.
**Option B:** This option is incorrect as biguanides do not increase insulin sensitivity.
**Option C:** This option is incorrect as biguanides do not primarily work by increasing the peripheral utilization of glucose.

**Clinical Pearl / High-Yield Fact**
Biguanides like metformin can cause lactic acidosis, a rare but serious side effect, particularly in patients with renal impairment or those who consume excessive alcohol.

**Correct Answer: B. Biguanides primarily decrease hepatic glucose production by inhibiting gluconeogenesis.**