Objective To assess the safety and convenience of injecting insulin through clothing. Design 20 week randomised cross over trial. Setting University hospital diabetes clinic in Detroit, Michigan, USA. Patients 50 patients who had type I or type II diabetes and had been injecting insulin for > 1 year. 42 patients (84%) (mean age 41 y, 50% women, 78% type I diabetes, 50% attended > 16 y formal education) with a mean duration of diabetes of 14 years completed the study.