Department of Health Promotion and Policy, University of Massachusetts Amherst, Amherst, MA, USA; Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK. Electronic address: jhartmannboy@umass.edu. Diabetes Research Centre, University of Leicester, UK. Warwick, UK. Department for Continuing Education, University of Oxford, Oxford, UK. National Institute for Health and Care Research Newcastle In Vitro Diagnostics Co-operative, Newcastle University, Newcastle, UK. Liverpool Reviews and Implementation Group, University of Liverpool, Liverpool, UK. Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK. Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK. Medical Sciences Division, University of Oxford, Oxford, UK. WHO, Los Angeles, CA, USA.