1. Obesity and Endocrinology Research Unit, Clinical Sciences Centre, University Hospital Aintree, University of Liverpool, Liverpool, U.K.
2. Diabetes and Endocrinology Department, St Helens and Knowsley Teaching Hospitals National Health Service Trust, Prescot, U.K.
3. Department of Biochemistry, Aintree University Hospitals National Health Service Foundation Trust, Liverpool, U.K.
4. Department of Nephrology, Aintree University Hospitals National Health Service Foundation Trust, Liverpool, U.K.
5. Department of Mathematics and Statistics, John Moores University, Liverpool, U.K.