The main study outcome measure is the incidence of ulcer recurrence. Ulcers are defined as cutaneous erosions through the dermis that may extend to involve the subcutaneous tissue or even to the level of muscle or bone [27, 28]. We expect at least a 30% reduction in the incidence of ulcer recurrence from baseline to the end of intervention.

The secondary outcome measures include (1) the change of barefoot dynamic plantar pressures, from the third to the sixth diaries compared with that from the first diary (screening period); (2) the influence of footwear adherence on ulcer recurrence; and (3) the incidence of cardiovascular events.