Which drug class is considered a first-line treatment for Type 2 diabetes mellitus?

The correct answer is biguanides, specifically metformin, which is recognized as a first-line treatment for Type 2 diabetes mellitus. Metformin works primarily by decreasing hepatic glucose production and increasing insulin sensitivity in peripheral tissues, which helps lower blood glucose levels effectively.

Biguanides are preferred for initial therapy due to their favorable profile, which includes not only efficacy in lowering blood glucose but also benefits such as weight neutrality or even weight loss and a low risk of causing hypoglycemia compared to other options. Additionally, metformin has beneficial effects on cardiovascular outcomes, making it a critical choice for many patients.

The other options, while effective in managing Type 2 diabetes, are typically not used as first-line treatments. Thiazolidinediones, for instance, can improve insulin sensitivity but may have associated risks such as weight gain and fluid retention. Insulin is often reserved for cases where oral medications aren’t sufficient or in more advanced stages of the disease. Sulfonylureas stimulate insulin secretion from the pancreas but carry a risk of hypoglycemia and weight gain as well. Therefore, biguanides stand out as the preferred initial therapy for the management of Type 2 diabetes.