Professor Greenfield is an Endocrinologist and Clinical researcher. He is Head of the Department of Endocrinology and Director, Diabetes Services, at St Vincent’s Hospital. His current positions and roles include: Clinical Associate Dean, St Vincent's Clinical School, Professor of Medicine, University of New South Wales; Editor-in-Chief, Endocrinology, Diabetes and Metabolism Case Reports; Editorial Board member, Clinical Obesity; Council Member, Australia and New Zealand Obesity Society.
He previously held an NHMRC Neil Hamilton Fairley Postdoctoral Research Fellowship, which allowed him to study in the Departments of Medicine and Clinical Biochemistry, University of Cambridge, Addenbrooke’s Hospital, Cambridge, UK (2005-6, Supervisors: Prof Stephen O’Rahilly and Dr Sadaf Farooqi). He undertook a PhD at the Garvan Institute from 2001-2004, under the supervision of Prof D Chisholm, Prof L Campbell and Prof K Samaras). He graduated from the Faculty of Medicine with Honours (class 1) from the University of NSW in 1995.