Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich-Heine University, Düsseldorf, Germany German Center for Diabetes Research, Düsseldorf, Germany. German Center for Diabetes Research, Düsseldorf, Germany Institute for Biometry and Epidemiology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich-Heine University, Düsseldorf, Germany. West-German Centre of Diabetes and Health, Verbund Katholischer Kliniken Düsseldorf, Düsseldorf, Germany. Department of Nutrition and Food Science, Nutritional Physiology, Rheinische Friedrich-Wilhelms-University, Bonn, Germany. Metabolic Unit, Institute of Biomedical Engineering, National Research Council, Padova, Italy. Novo Nordisk Foundation Center for Basic Metabolic Research, Department for Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark. Institute for Medical Microbiology and Hospital Hygiene, Heinrich-Heine University, Düsseldorf, Germany. Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE. Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE Department of Agricultural, Nutritional and Food Science, University of Alberta, AB, Canada Department of Biological Sciences, University of Alberta, Edmonton, Canada. Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich-Heine University, Düsseldorf, Germany German Center for Diabetes Research, Düsseldorf, Germany michael.roden@ddz.uni-duesseldorf.de schloot@ddz.uni-duesseldorf.de. Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich-Heine University, Düsseldorf, Germany German Center for Diabetes Research, Düsseldorf, Germany Department of Endocrinology and Diabetology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany michael.roden@ddz.uni-duesseldorf.de schloot@ddz.uni-duesseldorf.de.