Aims/hypothesis Youth with type 1 diabetes are at high risk for loss to follow-up during the transition from paediatric to adult diabetes care. Our aim was to assess the effect of a communication technology enhanced transition coordinator intervention compared with usual care on clinic attendance among transitioning youth with type 1 diabetes. Methods In this open label, pragmatic clinical trial of youth with type 1 diabetes, aged 17–18 years, transitioning from paediatric to adult diabetes care, the intervention group received support from a transition coordinator who used communication technology and the control group received usual care. The primary outcome was the proportion of individuals that did not attend at least one routine clinic visit in adult diabetes care within 1 year after transfer. Secondary outcomes included diabetes-related clinical outcomes and quality of life measures. Results There were no baseline differences in age, sex, HbA 1c and number of follow-up visits, emergency department visits and diabetic ketoacidosis admissions in the 1 year prior to transition between the usual care ( n  = 101) and intervention ( n  = 102) groups. In the year following transfer, 47.1% in the usual care group vs 11.9% in the intervention group did not attend any outpatient diabetes appointments ( p  < 0.01). There were no differences in glycaemic control or diabetic ketoacidosis post transfer. Conclusions/interpretation Our intervention was successful in improving clinic attendance among transitioning youth with type 1 diabetes. Importantly, this programme used simple, readily accessible communication technologies, which increases the sustainability and transferability of this strategy. Trial registration isrctn.org ISRCTN13459962 Graphical abstract