• Change from Baseline in Homeostatic Model Assessment - Beta cell. [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  

• Change from Baseline in Glycosylated Hemoglobin. [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in oral glucose tolerance testing. [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in Insulin. [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in Proinsulin. [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in C-peptide. [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in High sensitivity C-Reactive Protein. [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in Adiponectin. [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in Homeostatic Model Assessment - Sensitivity. [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in Triglycerides [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in Low Density Lipoprotein-Cholesterol [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in High Density Lipoprotein-Cholesterol [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  
• Change from Baseline in Total Cholesterol [ Time Frame: Week: 24 or Final Visit beyond week 12. ] [ Designated as safety issue: No ]
  

Tight glycemic control is mandatory for the prevention and treatment of vascular complications in patients suffering from diabetes mellitus. After onset of Type 2 Diabetes, patients are usually treated with diet along with or without different combinations of oral drugs. One first-line drug class are sulfonylurea drugs that are preferably provided to patients who are not obese. The mode of action of sulfonylurea drugs is to increase beta-cell secretion, but it could be shown that they lead to deterioration of the beta-cell secretion product over time, resulting in increased proinsulin secretion. Since proinsulin is an independent cardiovascular risk factor, recent publications have demonstrated an increased risk for cardiovascular events in patients treated with sulfonylurea drugs as compared to other treatment methods.

Combination therapy of sulfonylurea drugs with glitazones has been shown to counterbalance the effect of deteriorated beta-cell secretion and to improve insulin sensitivity and the levels of proinsulin, C-peptide and other laboratory surrogate markers for cardiovascular risk. Proving that the treatment of diabetic patients with higher doses of beta cytotropic agents can be avoided and beta-cell function can be preserved by using pioglitazone in combination with low dose sulfonylurea drugs, it will be possible to optimize the treatment of patients with type 2 diabetes who are not controlled efficiently by sulfonylurea drugs monotherapy.

In this study patients will be enrolled who are inefficiently treated with a Glimepiride monotherapy. Patients will be either randomized to a combinational therapy of Pioglitazone and Glimepiride or Glimepiride monotherapy. If possible, study medication will be up-titrated to maximal dosage levels in both treatment arms to observe maximal and comparable treatment effects. Stable effects on beta-cell function will be observed after 24 weeks of treatment.