Metformin is an oral antihyperglycaemic agent primarily used to manage type 2 diabetes mellitus by improving insulin sensitivity and reducing hepatic glucose production. Its clinical significance lies in its ability to lower blood glucose levels, reduce the risk of diabetes-related complications, and promote weight loss, making it a first-line treatment. A key association is its potential to cause gastrointestinal side effects, such as nausea and diarrhoea, particularly during initiation.