University of Oxford - Nuffield Department of Primary Care Health Sciences, University of Sheffield - Department of Infection, Immunity & Cardiovascular Disease, University of Aberdeen - Institute of Applied Health Sciences, University of Sheffield - School of Health and Related Research, University of Oxford - Diabetes Trial Unit, University of Sheffield - School of Health and Related Research, University of Sheffield - School of Health and Related Research, University of Leicester - Leicester Diabetes Centre, University of Sheffield - School of Health and Related Research, University of Oxford, University of Leicester - Leicester Diabetes Centre, National Institute for Health and Clinical Excellence (NHS) and University of Sheffield - School of Health and Related Research