Colin Dayan trained in medicine at University College, Oxford, and Guy’s and Charing Cross Hospitals in London, UK before obtaining a PhD in the immunology of Graves’ Disease in Laboratory of Marc Feldmann. He then spent a year as an endocrine fellow at the Massachussetts General Hospital in Boston, USA before completing his specialist training in diabetes and endocrinology as a Lecturer in Bristol. He became a consultant senior lecturer in medicine (diabetes/endocrinology) at the University of Bristol in 1995 and Head of Clinical Research at the Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology in Bristol in 2002. In 2010, he was appointed to the Chair of Clinical Diabetes and Metabolism and Head of Section at Cardiff University School of Medicine. He served as Director of the Institute of Molecular and Experimental Medicine in 2011 – 2015. In 2020 he was appointed part-time as a Senior Clinical Researcher in the Nuffield Department of Medicine at the University of Oxford and in 2021 as Director of the Joint Research Office for Cardiff University and Cardiff and Vale Health Board. He has also served as Secretary and Treasurer of the Association of Physicians of Great Britain and Ireland.
His research interests in thyroid disease include thyroid autoimmunity, thyroid hormone replacement and bioavailability, genetic epidemiology as applied to population variation in thyroid hormone bioavailability and thyroid eye disease. He was secretary of the European Thyroid Association 2013-2018 and executive committee member of the British Thyroid Association 2018-2022. He is currently a member of EUGOGO, Chair of the UK Thyroid Eye Disease Amsterdam Implementation Group and Chairman of Trustees of the Thyroid Eye Disease Charitable Trust.