Professor Farmer initially followed a career as a full-time but research active general practitioner (projects included work on screening for colorectal cancer, management of hypertension and screening for diabetes). In 2001 he was awarded an NHS R&D career development award gaining a wide range of post-doctoral academic experience in the Department of Primary Care Health Sciences at Oxford, and in all aspects of clinical trial design, conduct and analysis as a research fellow in the Diabetes Trials Unit. He now focuses on use of digital health technologies to improve health. His work includes the best use of blood glucose monitoring, personalising treatment, and developing and evaluating digital health applications to support self-management.
He has experience of leadership, at a national level, currently as Director of the NIHR HTA Programme. He was the founding director of the Primary Care Trials Unit at Oxford and Co-Director of NIHR Thames Valley CLRN until 2016. He was a member of the UK NICE Guideline Development Group for Type 2 Diabetes 2014-15 and the Steering Group of the James Lind Alliance, Diabetes UK Type 2 Diabetes Priority setting partnership in 2017. He continues to see patients as an associate GP of a local practice for one session a week.