Beyond clinical closure: functional skin barrier recovery to prevent diabetic foot ulcer recurrence: a narrative review.

Diabetic foot ulcer (DFU) recurrence remains common after apparent wound healing, partly because conventional endpoints define healing as complete epithelialization without drainage rather than as durable recovery of skin function. This narrative review proposes functional closure as a clinically useful extension of current DFU healing assessment. Functional closure refers to a post-healing state in which the regenerated ulcer site has recovered sufficient epidermal barrier competence to limit transepidermal water loss (TEWL), maintain stratum corneum hydration, tolerate minor mechanical trauma, and reduce microbial entry. Diabetes-related epidermal dysfunction, autonomic neuropathy, anhidrosis, xerosis, fissuring, altered lipid metabolism, impaired perfusion, and repetitive plantar loading may leave clinically closed ulcer sites biologically fragile. Emerging evidence linking elevated TEWL at recently closed chronic wounds and DFU sites with subsequent recurrence supports the incorporation of barrier assessment into post-closure risk evaluation. However, existing moisturizer and barrier-supporting studies have mainly demonstrated improvements in xerosis, hydration, and visible skin condition, and have not yet established a reduction in recurrent DFU. Post-healing DFU care should therefore move beyond the binary distinction between an open and a closed wound toward active maintenance of durable remission. Future trials should test targeted barrier-repair strategies in risk-enriched patients with high TEWL, poor hydration, fissuring, callus, fragile scar skin, or other signs of incomplete functional closure, while integrating barrier assessment with offloading, plantar pressure evaluation, temperature monitoring, vascular assessment, infection surveillance, and professional foot care. This framework may help shift DFU management from treating recurrent breakdown to preserving long-term barrier-competent healing. Importantly, functional closure is also framed as an immunologically competent barrier state, in which the healed surface limits persistent irritant- and microbe-driven activation of innate immune pathways rather than merely appearing epithelialized or hydrated. TEWL should be interpreted as one component of barrier recovery rather than as a single surrogate definition of functional closure, and the proposed framework remains a conceptual model requiring prospective validation.