© 2014 Springer-Verlag Berlin Heidelberg. Purpose: Exercise training in healthy volunteers rapidly improves vascular function, preceding structural remodelling. No study examined the time-course of such adaptations in subjects with a priori endothelial dysfunction. Methods: We examined brachial artery endothelial and smooth muscle function using flow-mediated dilation (FMD) and glyceryl trinitrate (GTN) administration in 13 type 2 diabetes patients (59 ± 6 years) and 10 healthy subjects (58 ± 7 years) before, during (2-weekly) and after an 8-week training programme. Arterial structure was assessed via peak blood flow and artery diameter. Results: Training increased peak oxygen uptake (P = 0.03), comparable between groups (P = 0.276). We observed a similar impact of training on brachial artery vasomotor function across the training period in diabetes patients and controls (FMD/GTN-ratio), with a higher FMD/GTN-ratio at 2, 6 and 8 weeks (P = 0.036). Artery diameter, peak blood flow or peak diameter had not changed after training. Conclusion: Training leads to rapid improvement in brachial artery vascular function in diabetes patients and controls. In contrast to previous observations in healthy young subjects, the increase in function was preserved after 8 weeks of training in middle-aged diabetes patients and controls, suggesting a different time-course in vascular adaptations in subjects with endothelial dysfunction.