Metformin is an oral biguanide medication primarily used to manage type 2 diabetes by lowering blood sugar levels. It works by reducing glucose production in the liver, decreasing intestinal glucose absorption, and improving the body's sensitivity to insulin, thereby enhancing glucose uptake in cells. Approved by the FDA in 1994, it serves as the first-line treatment recommended by the American Diabetes Association for adults and children over 10 when diet and exercise alone prove insufficient. Off-label, metformin aids in polycystic ovary syndrome (PCOS) by lowering insulin and androgen levels to regulate menstrual cycles and improve fertility. It also shows promise in prediabetes prevention and modest weight loss benefits for obese patients without causing hypoglycemia. Available in immediate-release and extended-release formulations, metformin is taken with meals to optimize efficacy.