12 Weeks Treatment With 3 Different Doses of BI 10773 in Type 2 Diabetic Patients

Inclusion Criteria: * Male and female patients with a diagnosis of type 2 diabetes mellitus * either treatment-naïve or on a maximum of 1 oral antidiabetic therapy on a stable dose for the10 weeks prior to screening * HbA1c ≥6.5 to ≤9.0% and for treatment-naïve patients:HbA1c \>7.0 to ≤10.0% * HbA1c \>7.0 to ≤10.0% at Visit 2 (start of run-in) for all patients * Age between 18 and 80 years * BMI less than 40 kg/m2 * Signed and dated informed consent prior to admission to the study in accordance with GCP and local legislation Exclusion Criteria: 1. Myocardial infarction, stroke or TIA within 6 months prior to informed consent 2. Impaired hepatic function 3. Renal insufficiency or impaired renal function 4. Disease of central nervous system, or psychiatric disorders or clinically relevant neurologic disorders that may interfere with trial participation 5. Chronic or clinically relevant acute infections 6. Current or chronic urogenital tract infection determined by medical history 7. History of clinically relevant allergy/hypersensitivity 8. Treatment with glitazones, GLP-1 analogues or insulin within 3 months prior to informed consent 9. Treatment with anti obesity drugs 10. Current treatment with systemic steroids 11. Alcohol abuse 12. Treatment with an investigational drug within 2 months prior to informed consent 13. known intolerance to metformin 14. Dehydration 15. Unstable or acute CHF 16. Acute or chronic acidosis 17. Hereditary galactose intolerance 18. Woman of child bearing potential who are nursing or pregnant or not practicing an acceptable method of birth control