Efficacy and Safety of BI 1356 BS (Linagliptin) in Combination With Metformin in Patients With type2 Diabetes

Inclusion criteria: Inclusion\_Criteria: * Male and female patients with a diagnosis of type 2 diabetes mellitus and previo usly treated with metformin alone or with metformin and one other oral antidiabetic d rug * HbA1c 7.0 9.0% at screening for patients treated with metformin and one other oral antidiabetic drug * HbA1c 7.5 10.0% at screening for patients treated with metformin alone * HbA1c 7.5 10.0% at beginning of the placebo run-in phase * Age \> 21 and \< 75 years * MI \> 25 and \< 40 kg/m2 (Body Mass Index) Exclusion criteria: Exclusion\_Criteria: * Clinically relevant cardiovascular disease * Impaired hepatic function * Renal insufficiency or impaired renal function * Treatment with rosiglitazone or pioglitazone within 6 months prior to screening * Treatment with insulin within 3 months prior to screening