To investigate bioavailability of BI 187004 and of metformin after concomitant multiple oral administration of 240 mg BI 187004 q.d. and 1000 mg metformin b.i.d. in comparison to BI 187004 and metformin given alone.

Inclusion criteria:

1. Healthy male subjects
2. Subjects must be able to understand and comply with study requirements
3. Age of 18 to 50 years
4. Body mass index (BMI) of 18.5 to 29.9 kg/m2

Exclusion criteria:

1. Any finding in the medical examination (including BP, pulse rate (PR) or ECG) is deviating from normal and judged as clinically relevant by the investigator
2. Repeated measurement of systolic blood pressure outside the range of 90 to 140 mmHg or diastolic blood pressure outside the range of 50 to 90 mmHg, or pulse rate outside the range of 50 to 90 bpm
3. Any laboratory value outside the reference range that the investigator considers to be of clinical relevance
4. Any evidence of a concomitant disease judged as clinically relevant by the investigator
5. Gastrointestinal, hepatic, renal, respiratory, cardiovascular, metabolic, immunological or hormonal disorders
6. Surgery of the gastrointestinal tract that could interfere with kinetics of the trial medication (except appendectomy and simple hernia repair)
7. Diseases of the central nervous system (such as epilepsy), other neurological disorders or psychiatric disorders