Linagliptin Versus Placebo in Type 2 Diabetic Patients With Inadequate Glycaemic Control on Metformin in Combination With Pioglitazone

Inclusion criteria: 1. Diagnosis of diabetes mellitus prior to informed consent 2. Patients treated with metformin and pioglitazone (therapy should be unchanged for 12 weeks) 3. Glycosylated haemoglobin A1 \>= 7.5% and \<= 10% 4. Age between 18 and less than 80 5. \- Body Mass index less or equal to 45 Exclusion criteria: 1. Uncontrolled hyperglycaemia during run in period 2. Myocardial infarction, stroke or transient ischaemic accident within 3 months prior to informed consent 3. Impaired hepatic function 4. Gastric by pass surgery 5. Treatment with roziglitazone, GLP 1 analogues, DPP-4 inhibitors or insulin within 3 months prior to informed consent 6. Treatment with anti-obesity drugs 7. Current treatment with systemic steroids at the time of informed consent or change in dosage of thyroid hormones within 6 weeks prior to informed consent 8. Premenopausal women 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 during the trial