Which of the following drug does not cause hypoglycemia: September 2008, March 2013
**Core Concept**
Metformin, sulfonylureas, and insulin are known to cause hypoglycemia due to their mechanism of action. Sulfonylureas stimulate insulin release from pancreatic beta cells, while insulin directly lowers blood glucose levels. Metformin, on the other hand, decreases hepatic glucose production and increases insulin sensitivity, but does not directly lower blood glucose levels.
**Why the Correct Answer is Right**
Metformin works by inhibiting the mitochondrial respiratory chain enzyme, **succinate dehydrogenase** (Complex II), which decreases hepatic glucose production. However, it does not stimulate insulin release or directly lower blood glucose levels, thus reducing the risk of hypoglycemia.
**Why Each Wrong Option is Incorrect**
**Option A:** Sulfonylureas stimulate insulin release from pancreatic beta cells, making them a cause of hypoglycemia.
**Option B:** Insulin directly lowers blood glucose levels, making it a well-known cause of hypoglycemia.
**Option C:** Meglitinides, like repaglinide, also stimulate insulin release from pancreatic beta cells, leading to hypoglycemia.
**Clinical Pearl / High-Yield Fact**
Metformin is often the first-line treatment for type 2 diabetes due to its safety profile, including a lower risk of hypoglycemia compared to other oral agents.
**Correct Answer: D. Metformin.**