A phase III randomised, double-blind parallel group extension study to investigate the efficacy and safety of twice daily administration of the free combination of linagliptin 2.5 mg + metformin 500 mg or of linagliptin 2.5 mg + metformin 1000 mg versus monotherapy with metformin 1000 mg twice daily over 54 weeks in type 2 diabetic patients previously completing the double-blind part of study 1218.46

Inclusion criteria:

• Signed and dated written informed consent, at the latest by the date of Visit 1
• Patients completing the entire treatment period of the double-blind study 1218.46, who are not treated with rescue medication (Visit 7)

Exclusion criteria:

• Patients who meet one or more of the withdrawal criteria of the treatment period of the previous study 1218.46
• Pre-menopausal women (last menstruation equal or less than 1 year prior to signing informed consent) who:
• are nursing or pregnant,
• or are of child-bearing potential and are not practicing an acceptable method of birth control, or do not plan to continue using this method throughout the study and do not agree to submit to periodic pregnancy testing during participation in the trial. Acceptable methods of birth control include transdermal patch, intra uterine devices/systems (IUDs/IUSs), oral, implantable or injectable contraceptives, sexual abstinence and vasectomised partner and in addition for male partners a barrier method, such as the use of condom with spermicide. No exception will be made.
• Alcohol abuse within the 3 months prior to informed consent that would interfere with study participation
• Drug abuse that in the opinion of the investigator would interfere with trial participation
• Any other clinical condition which, in the opinion of the investigator, would not allow safe completion of the protocol and safe administration of the study medication