Chronic diabetic foot ulcers remain one of the most stubborn problems in wound care. Even with the cornerstones of treatment—debridement, offloading, infection control, and vascular optimization—a substantial proportion of wounds fail to close within the expected timeframe. This has driven interest in adjunctive therapies that target the biology of impaired healing itself. Photobiomodulation (PBM), historically called low-level laser therapy (LLLT), is one such approach. It uses red and near-infrared light to stimulate cellular activity in the wound bed, and a growing body of controlled trials has examined whether it can meaningfully accelerate closure of diabetic foot ulcers.
What Photobiomodulation Is and How It May Work
Photobiomodulation delivers low-intensity light—typically in the red (around 630–660 nm) and near-infrared (around 810–830 nm) wavelengths—to tissue at doses too low to cause heating or cutting. Unlike surgical lasers, the goal is not to ablate tissue but to trigger biochemical changes within cells.
The leading explanation involves absorption of light by mitochondrial cytochrome c oxidase, which increases cellular energy production and modulates reactive oxygen species and signaling pathways. Laboratory studies of diabetic fibroblasts show that PBM can enhance cell proliferation, migration, and collagen production, and can promote the differentiation of fibroblasts into myofibroblasts that contract and close a wound. Work examining diabetic wound models has linked 660 nm irradiation to activation of the Ras/MAPK signaling pathway and to a more favorable growth-factor and cytokine profile (Houreld and colleagues). Several reviews also describe reduced inflammation and decreased cellular apoptosis as contributing mechanisms. In diabetes, where fibroblast dysfunction, persistent inflammation, and poor angiogenesis all impair repair, these cellular targets are biologically plausible reasons to expect benefit.
What the Clinical Evidence Shows
Two systematic reviews with meta-analysis published in 2021 provide the most useful summary of the randomized evidence. Dos Santos and colleagues, writing in the International Journal of Lower Extremity Wounds, pooled 13 randomized controlled trials and reported that LLLT was associated with faster and more complete ulcer healing compared with standard care alone. In the same year, Huang and colleagues, in the International Wound Journal, analyzed 13 randomized trials involving more than 400 patients and found that LLLT significantly increased the complete healing rate—roughly doubling it relative to controls (risk ratio approximately 2.1)—while also reducing ulcer area and shortening mean healing time.
Taken together, these analyses point in a consistent direction: as an add-on to conventional wound care, PBM appears to improve the likelihood and speed of closure for many diabetic foot ulcers. Some datasets have additionally suggested fewer wound infections in treated groups, though this finding is less firmly established.
Important Limitations and Cautions
Encouraging pooled results should be read alongside a clear caveat: the quality of the underlying evidence is low. Reviewers applying the GRADE framework have rated the certainty of these findings as low to very low, reflecting small sample sizes, differences in how trials were conducted and blinded, and a high risk of bias in several studies. Just as important, the trials vary widely in their treatment parameters—wavelength, energy density (fluence), power, and number of sessions—which makes it difficult to define a single optimal protocol. Laboratory data suggest the response is both wavelength- and dose-dependent, with red wavelengths near 630–660 nm and modest fluences performing well in cell studies, but these findings have not yet translated into standardized clinical dosing.
For these reasons, photobiomodulation is best understood as a promising adjunct rather than a replacement for established care. It does not substitute for pressure offloading, debridement, management of infection, or assessment and treatment of peripheral arterial disease—the interventions with the strongest evidence for healing and limb preservation. Major diabetic foot guidelines continue to prioritize those measures, and where light-based therapies are considered, they are positioned as supplementary options in wounds that are not progressing despite good standard care.
Clinical Takeaways
Photobiomodulation is a low-risk, noninvasive therapy with a coherent biological rationale and meta-analytic signals of benefit for diabetic foot ulcer healing. The current evidence, however, rests on small trials of variable quality and inconsistent dosing, so conclusions should be regarded as preliminary. In practice, PBM may have a role as an adjunct to—never a substitute for—the foundational elements of diabetic foot care. Larger, well-designed randomized trials with standardized treatment parameters are needed before it can be recommended as a routine component of wound management.
References
Dos Santos CM, da Rocha RB, Hazime FA, Cardoso VS. A Systematic Review and Meta-Analysis of the Effects of Low-Level Laser Therapy in the Treatment of Diabetic Foot Ulcers. International Journal of Lower Extremity Wounds. 2021.
Huang J, Chen J, Xiong S, Huang J, Liu Z. The effect of low-level laser therapy on diabetic foot ulcers: A meta-analysis of randomised controlled trials. International Wound Journal. 2021;18(6):763–776.
Oyebode O, Houreld NN, Abrahamse H. Photobiomodulation in diabetic wound healing: A review of red and near-infrared wavelength applications on cell viability, migration, apoptosis, and collagen synthesis. Journal of Biophotonics / Frontiers in Photonics. 2021–2024.
Houreld NN et al. Photobiomodulation at 660 nm Stimulates In Vitro Diabetic Wound Healing via the Ras/MAPK Pathway. Cells. 2023;12(7):1080.
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