With the development of society and the economy, the incidence of diabetic foot ulcers continues to increase. Currently, conventional debridement with dressing changes, hyperbaric oxygen, and vacuum sealing drainage are the main conservative treatments in clinical practice, and large wounds often require skin grafts or skin flap grafts. However, the treatment effects are not ideal, and many complications exist. Due to its complex pathogenesis, long treatment time, significant associated difficulties, and high disability rate, diabetic foot ulcers cause a heavy burden to patients, society, and medical care. According to our previous study, the pharmacological effects of human umbilical cord blood stem cells include nonspecific immune regulation; increased secretion of growth factors, vasoactive factors, and anti-inflammatory factors; enhanced anti-infectious ability of the human body; elimination of inflammation; and promotion of angiogenesis and ulcer healing. These effects suggest stem cells may be useful as an autologous or allogeneic treatment for refractory wounds. Therefore, we are conducting a clinical trial to treat refractory diabetic wounds with human umbilical cord stem cells in our clinic for diabetic foot ulcer patients who meet the inclusion criteria.