Diabetic Foot Ulcers: New Test Detects ‘Invisible’ Healing Issues

Breakthrough Measures Skin Barrier Function to Predict Re-Opening Risk

A novel approach to assessing diabetic foot ulcer (DFU) healing focuses not on how wounds *look*, but on what the skin subtly *reveals* – a measure of moisture loss that can predict whether an ulcer is truly closed or poised to re-open, potentially averting amputation.

Unveiling ‘Invisible Wounds’

Researchers led by Chandan K. Sen, PhD, MS, director of the McGowan Institute for Regenerative Medicine at the University of Pittsburgh, have developed a noninvasive tool to measure transepidermal water loss (TEWL). This assesses skin barrier function, identifying DFUs that appear healed but remain vulnerable beneath the surface.

The current US Food and Drug Administration definition of wound closure – intact skin with no drainage for two weeks – may be insufficient. Sen refers to these cases as “invisible wounds,” where impaired skin barrier function goes undetected. The new device quantifies water vapor escaping from the skin, providing an objective measure.

A Significant Problem

Approximately 31% of individuals with DFUs ultimately require amputation, and nearly half of those patients do not survive beyond five years. Ulcer recurrence is a major driver of this outcome, often occurring at the same site shortly after apparent closure.

According to the CDC, approximately 37.3 million Americans have diabetes, and 20% of those will develop a foot ulcer during their lifetime. CDC Data (2024)

“These findings echo previous calls in the literature to reframe wound healing as the beginning of remission rather than resolution.”

—Chandan K. Sen, PhD, MS

TEWL as a Predictor of Recurrence

In a study published in Diabetes Care, researchers used a handheld evaporimeter to measure water loss from DFUs that had achieved visual closure. Wounds with elevated TEWL values – indicating greater skin permeability – were significantly more likely to reopen compared to those with TEWL levels similar to healthy skin.

This physiologic marker offers a reproducible measure of skin barrier recovery, distinguishing between “cosmetically healed” wounds and those that are functionally sound. The TEWL approach emphasizes barrier restoration, not just epidermal reepithelialization.

Implications for Patient Care

The TEWL measurement could help clinicians determine which patients might benefit from continued offloading, advanced wound care dressings, or antimicrobial protection, even after a wound appears healed. This aligns with a growing trend toward long-term management and prevention in diabetic foot care.

Sen and his team suggest integrating TEWL as a complementary endpoint in both clinical care and regulatory definitions of healing. If validated in larger studies, TEWL could become a standard component of diabetic foot protocols, potentially reducing preventable amputations.

Ultimately, visual closure may be viewed as the start of a carefully monitored remission, guided by the subtle signal of water loss through the skin.