Effects of Monochromatic Infrared Light on Painful Diabetic Polyneuropathy: Randomized Controlled Trial.

Purpose: To evaluate the effect of 890 nm Monochromatic Infrared Light (MIR) associated with a physical therapy protocol on pain in individuals with diabetic Distal Symmetric Polyneuropathy.

Methods: Randomized, parallel, double-blind controlled trial conducted with individuals randomly allocated into two groups: an experimental group (EG) with the application of 890 nm MIR associated with physical therapy and a control group that received the same treatment protocol without MIR application. Both groups underwent 18 treatment sessions and were followed up for 10 weeks. Pain assessment took place at four times using the instruments: Leeds Assessment of Neuropathic Symptoms and Signs, Douleur Neuropathique 4, and Brief Pain Inventory. Descriptive, inferential statistics and probabilistic estimates of the magnitude of the intervention's effect on neuropathic pain were used in data analysis (5% significance level).

Results: A total of 144 patients were allocated to groups. Lower levels of pain were observed for the EG after 6 weeks of intervention (p < .001) and 30 days after the intervention ended (p < .001). Pain intensity was lower and sleep quality improved (p < .001) for the experiment group, especially in people with severe pain.

Conclusions: 890 nm MIR associated with a physical therapy protocol alleviated pain in people with Diabetic Painful Polyneuropathy after 6 weeks of follow-up, showing to be a promising alternative for the control of neuropathic pain due to diabetes mellitus.

Clinical implications: 890 nm MIR improves Painful Diabetic Polyneuropathy patient care due to relief of neuropathic pain.