What is the primary mechanism of action for metformin?

Metformin primarily works by reducing hepatic glucose production, which is a critical mechanism in managing type 2 diabetes. It primarily acts on the liver to decrease the amount of glucose that is produced and released into the bloodstream, particularly by inhibiting gluconeogenesis. This is key because excess glucose production contributes to hyperglycemia in individuals with insulin resistance.

Moreover, metformin enhances insulin sensitivity in peripheral tissues, which helps facilitate better glucose uptake by the muscles and other cells, but it does not directly increase insulin secretion from the pancreas. By effectively lowering liver-derived glucose levels, metformin helps manage blood sugar levels, making it a cornerstone of diabetes treatment.

Other mechanisms and actions of metformin, such as mild intestinal glucose absorption reduction and potential slight effects on promoting gut microbiota changes, further support its effectiveness in lowering blood glucose, but the primary action remains its influence on hepatic glucose output.