Metformin is a biguanide and the first-line oral antihyperglycaemic agent that reduces hepatic glucose production, decreases intestinal glucose absorption, and improves peripheral insulin sensitivity. The prolonged-release formulation offers improved gastrointestinal tolerability and once-daily dosing convenience. Indicated for the treatment of type 2 diabetes mellitus, particularly in overweight patients, as monotherapy when diet and exercise fail to provide adequate glycaemic control, or in combination with other oral antidiabetics or insulin.