[1] Univ London Imperial Coll Sci Technol & Med, Fac Med, London, England
[2] Univ Cambridge, Inst Metab Sci, Cambridge, England
[3] Univ Sheffield, Dept Human Metab, Sheffield, S Yorkshire, England
[4] Kings Coll London, Diabet & Nutr Sci Div, London WC2R 2LS, England
[5] Univ Southampton, Fac Med, Southampton SO9 5NH, Hants, England