1. Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic, Rochester, MN 55905, USA
2. Department of Laboratory Medicine and Pathology Mayo Clinic, Rochester, MN 55905, USA
3. Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, B15 2TT, UK
4. Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TT, UK
5. Department of Endocrinology, Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2TT, UK