Photobiomodulation with or without ILIB in diabetic peripheral neuropathy: a randomized pilot trial.

Diabetic peripheral neuropathy is a disabling chronic complication of diabetes mellitus, associated with neuropathic pain, sensory dysfunction, and reduced quality of life. Because pharmacological treatments often provide only partial relief, photobiomodulation therapy (PBMT) has emerged as a promising non-pharmacological strategy with metabolic, anti-inflammatory, and neuromodulatory effects. To assess the feasibility of local PBMT, administered alone or combined with intravascular laser irradiation of blood (ILIB), and to explore preliminary short-term changes in neuropathic pain, neuropathic symptoms, and sensory responses in individuals with diabetic peripheral neuropathy. This prospective randomized controlled pilot trial included 26 participants allocated to three groups: local PBMT, local PBMT combined with ILIB, and sham control. All randomized participants completed 12 sessions over 23 days. Neuropathic pain intensity was assessed using the Visual Analog Scale, and neuropathic symptoms were evaluated using the Michigan Neuropathy Screening Instrument. Friedman and McNemar tests were used for exploratory within-group and paired analyses, and a linear mixed-effects model evaluated pain trajectory over time. Neuropathic pain intensity decreased across the five assessment points (p < 0.001), with significant intragroup reduction in the local PBMT group (p = 0.007). Improvements were observed in selected symptoms, including numbness, cramps, and dry skin with fissures. The mixed-effects model showed a significant effect of time on pain reduction (beta = -0.78; p = 0.001), although no significant group x time interaction was detected. Local PBMT, administered alone or combined with ILIB, was feasible in this outpatient pilot trial and was followed by preliminary short-term reductions in neuropathic pain and selected neuropathic symptoms. However, no definitive between-group superiority was demonstrated, and the findings should be interpreted cautiously because of the pilot design, small sample size, heterogeneity in baseline pain intensity, potential placebo effects, and short follow-up period.