What is the primary mechanism of action of Metformin?

The primary mechanism of action of Metformin is that it decreases hepatic gluconeogenesis. Metformin is a biguanide and is primarily used in the management of type 2 diabetes mellitus. It works predominantly by reducing the amount of glucose produced by the liver (gluconeogenesis), which helps lower blood sugar levels. This mechanism is particularly important because one of the key issues in type 2 diabetes is the overproduction of glucose by the liver, even when insulin is present.

By decreasing hepatic gluconeogenesis, Metformin helps improve insulin sensitivity in peripheral tissues and reduces insulin resistance, which is a central problem in type 2 diabetes. Furthermore, while Metformin does enhance the uptake of glucose by the muscles and may have a mild effect on intestinal glucose absorption, its defining characteristic is its action on the liver's gluconeogenic process.

The other mechanisms mentioned, such as increasing insulin secretion or stimulating pancreatic beta cells directly, are not actions associated with Metformin. Instead, these are characteristics of other classes of diabetes medications, such as sulfonylureas.