1. Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), 14558 Nuthetal, Germany
2. German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany
3. Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich, University of Tübingen, 72074 Tübingen, Germany
4. Department of Internal Medicine IV, University Hospital Tübingen, 72076 Tübingen, Germany
5. Institute of Nutritional Sciences, University of Potsdam, 14558 Nuthetal, Germany