Summary: In a double-blind dose-response trial in diabetic foot ulcers, red (660 nm) and infrared (904 nm) laser therapy at several doses all reduced ulcer size over time, but there was no significant difference between the groups, so no single wavelength or dose proved superior.
PICO Summary
| Element | Detail |
|---|---|
| Population | Adults with non-infected diabetic foot ulcers on conventional wound care; randomised, double-blind trial, Brazil. |
| Intervention | 660 nm low-level laser at one of three energy densities (4, 8, or 12 J/cm²), twice weekly for 10 weeks, plus standard care. |
| Comparison | 904 nm infrared laser (10 J/cm²) as the control arm, also with standard care. |
| Outcome | There was no statistically significant difference in ulcer-area reduction between groups at 5 weeks (p=0.2582) or 10 weeks (p=0.1164). Within each group, ulcer size fell significantly over time (p<0.0001). Regardless of wavelength, 8–12 J/cm² achieved a 50% area reduction, while the lowest red dose (4 J/cm²) had fewer responders. |
Expert Commentary
This trial must be read with the between-group result in front, because that is what tests the question and it was negative: there was no significant difference in ulcer reduction between the red-light doses and the infrared control at either five or ten weeks. The within-group improvement over time is real but far weaker evidence, since ulcers on good standard care often shrink anyway and every arm here also received conventional therapy, so attributing healing specifically to a given wavelength or dose is not supported. The most defensible practical signal is internal to the laser arms, that energy densities of 8 to 12 J/cm² produced more responders than the lowest 4 J/cm² dose, which speaks to dosing if photobiomodulation is used at all rather than proving it beats no laser. The absence of a true no-laser control is a real limitation, as is the modest size implied by four arms. Can I use this with my patients? Only cautiously. This does not establish that 660 nm laser adds benefit over standard wound care, so I would not adopt it on this basis, and if a unit is already in use I would at least favour an adequate dose in the 8 to 12 J/cm² range while keeping offloading, debridement, and infection control central.
References
Bezerra Miranda M, Silva Barros AC, Veloso Coelho L, et al. Dose-response and efficacy of 660-nanometer low-level laser therapy in healing diabetic foot ulcers: a randomized, double-blind, clinical trial. Lasers Med Sci. 2025;40(1):399. doi:10.1007/s10103-025-04641-2