Diabetes-related foot ulceration is a frequent cause for hospital admission and the leading cause of nontraumatic lower limb amputation, placing a high burden on the health system, patient, and their families. Considerable advances in treatments and the establishment of specialized services and teams have improved healing rates and reduced unnecessary amputations. However, amputation rates remain high in some areas, with unacceptable variations within countries yet to be resolved. Specific risk factors including infection, ischemia, ulcer size, depth, and duration as well as probing to bone (or osteomyelitis), location of ulcer, sensory loss, deformity (and high plantar pressure), advanced age, number of ulcers present, and renal disease are associated with poor outcome and delayed healing. To assist in prediction of difficult-to-heal ulcers, more than 13 classification systems have been developed. Ulcer depth (or size), infection, and ischemia are the most common risk factors identified. High-quality treatment protocols and guidelines exist to facilitate best practice in the standard of care. Under these conditions, 66%-77% of foot ulcers will heal. The remaining proportion represents a group unlikely to heal and who will live with a non-healing wound or undergo amputation. The authors have applied their experience of managing patients in this discussion of why some ulcers are harder to heal. The article explores the effects of patient non-adherence to treatment, comorbid mental illness, a failure of research to be translated into the everyday practice of many clinicians, and the impact of delayed access to specialized treatment. These factors when combined with the main published risk factors of size, infection, ischemia and pressure are perceived as critical barriers to healing.