Introduction Diabetes is a chronic disease amenable to management in the community and outpatient setting. The increasing incidence of diabetes places outpatient endocrinology services under pressure to provide a quality service in a timely manner. Our aim was to apply lean thinking to the diabetes clinic in a tertiary referral centre in the West of Ireland to improve flow, as reflected in reduced patient journey times. Methods The project lasted 6 months, from January to June 2011. An introductory seminar on lean thinking was arranged to inform and motivate the Diabetes Day Centre staff. Two ‘rapid improvement events’ took place. Value stream mapping (VSM) was the predominant lean tool employed. Patient journeys were mapped and quantified (minutes) using timesheets allocated to each step in the process at baseline, and following intervention. Data were analysed using Minitab V.16.0. Results VSM allowed the value-adding and problem-causing steps in the patient journey through the diabetes clinic process to be identified and addressed. Total patient journey time through the clinic was significantly reduced from 118 (±38.02) min to 58 (±18.30) min (p