1 Institute for Diabetes and Obesity, Helmholtz Diabetes Center & German Center for Diabetes Research (DZD), Helmholtz Zentrum München, Munich, Germany.
2 Division of Metabolic Diseases, Department of Medicine, Technische Universität München, Munich, Germany.
3 Molecular Physiology Group, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
4 Department of Chemistry, Indiana University, Bloomington, Indiana, USA.