The rationale of the study is to investigate the effect of glargine and metformin treatment compared to sulfonylurea and metformin treatment and compared to DPP-4 inhibitor and metformin treatment on postprandial intact proinsulin release and postprandial PAI-1 levels. Accompanying a comparison of postprandial intact proinsulin release and the time course of postprandial PAI-levels in between all three antidiabetic treatment groups and a non-diabetic control group will be performed as well.