How does metformin lower blood glucose levels?

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An anatomical illustration of the human pancreas shows its location near the stomach and intestines, a detailed cross-section highlighting ducts and the islet of Langerhans, and an inset of pancreatic tissue histology with labeled alpha, beta, and delta cells. — diabetes mellitus The islets of Langerhans are responsible for the endocrine function of the pancreas. Each islet contains beta, alpha, delta, and pancreatic polypeptide (PP) cells that are responsible for the secretion of pancreatic hormones. Beta cells secrete insulin, a well-characterized hormone that plays an important role in regulating glucose metabolism.

Metformin is classified as an antihyperglycemic agent, meaning it helps lower blood glucose levels without typically causing hypoglycemia. It functions through two primary mechanisms:

Decreasing hepatic glucose production: It reduces the amount of glucose produced by the liver.
Improving insulin sensitivity: It increases the action of insulin on muscle and adipose (fat) tissues, allowing the body to utilize glucose more effectively.1

While effective, metformin use carries a risk of lactic acid accumulation in the blood and tissues, which can be a serious side effect.1