The number of antidiabetic medicines used in the treatment of diabetes type 2 is still growing. In the article, five main groups of oral antidiabetic medicines are described. According to the recommendation of the American Diabetes Association and the European Association for the Study of Diabetes the therapy of diabetes should be slowly modified. At every stage of diabetes treatment lifestyle changes and metformin are recommended. The key role of metformin is related to the fact that metformin is effective, safe and assessed in many clinical trials. The indications for metformin are still expanding. At present, in some countries metformin is used not only in the treatment of diabetes but also in the prevention of diabetes type 2. In the article the recommendations of different scientific associations concerning pharmacotherapy of diabetes type 2 at different stages of the disease are presented.