1. Research
Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, German Research Center for Environment Health, Neuherberg, D-85764, Germany
2. German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
3. Division
of Clinical Chemistry and Pathobiochemistry (Central Laboratory), University Hospital Tübingen, Tübingen, D-72076, Germany
4. Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen (IDM), D-72076 Tübingen, Germany
5. Department
of Internal Medicine, Division of Endocrinology, Diabetology, Nephrology,
Vascular Disease and Clinical Chemistry, University Hospital of the Eberhard Karls University, D-72076 Tübingen, Germany
6. Chair
of Analytical Food Chemistry, Technische Universität München, Freising-Weihenstephan, D-85354, Germany