The sequelae and complications associated with type 2 diabetes mellitus can be reduced or inhibited by optimal therapy. Currently, a variety of medications are available for differentiated therapy, which should be used according to the German Diabetes Association Guidelines. Changes in lifestyle represent the basic therapeutic principle, and it is mandatory to continuously maintain these measures throughout life. If this is not adequately effective (HBA(1c) <6.5%), treatment with oral antidiabetic drugs (OAD) is necessary. Over time OAD monotherapy frequently fails, so that a combination of several oral antidiabetics is needed. The choice of oral antidiabetics is particularly dependent on the patient's body mass index and associated diseases. If combination therapy with OAD is not successful in achieving HbA1c values <6.5%, insulin therapy is required either in combination with OADs as a bedtime regimen or as intensive insulin therapy using both basal and short-term acting insulins.