1 Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK; Department of Bioengineering, Imperial College London, London, UK; Hammersmith Hospital, London W12 0NN, UK. Electronic address: v.salem@imperial.ac.uk.
2 Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK.
3 Medical Education Research Unit, Imperial College London, London, UK.