What is the primary mechanism of action of metformin?

Metformin primarily acts by decreasing hepatic gluconeogenesis, which refers to the process by which the liver produces glucose from non-carbohydrate sources. By suppressing gluconeogenesis, metformin effectively reduces the total production of glucose in the body, which is especially beneficial in the management of type 2 diabetes mellitus.

In addition to this primary mechanism, metformin also enhances insulin sensitivity in peripheral tissues, such as muscle and adipose tissue, which helps to lower blood glucose levels. This dual action contributes to its effectiveness in managing hyperglycemia. The drug has minimal effects on insulin secretion, which distinguishes it from other antidiabetic medications that primarily work through increasing insulin production.

The other options do not accurately reflect metformin's mechanism of action. For instance, increasing hepatic gluconeogenesis would have the opposite effect of what is desired in diabetes management. Inhibition of Na/K ATPase and having alpha and beta agonist activity are mechanisms associated with other classes of drugs, such as certain diuretics and sympathomimetics, respectively, rather than metformin.