Home-Based Transcranial Direct Current Stimulation in Painful Diabetic Peripheral Neuropathy: A Double Blinded, Randomized, Low-Intensity Sham-Controlled Crossover Trial.

OBJECTIVES: To evaluate the analgesic effect of four weeks home-based transcranial direct current stimulation (tDCS) compared with low-intensity sham stimulation in individuals with type 1 diabetes mellitus and painful diabetic peripheral neuropathy. MATERIALS AND METHODS: A total of 35 participants with type 1 diabetes mellitus and painful diabetic peripheral neuropathy were enrolled in a home-based, randomized, double-blind, sham-controlled, crossover study. Each participant underwent four weeks of active (2 mA) and sham (0.3 mA) tDCS in a randomized order. Clinical and experimental end points were assessed before and after each treatment. The primary end point was pain relief, measured daily using a numeric rating scale. Secondary end points included various questionnaires. Quantitative sensory testing was used to assess the pain system. RESULTS: No significant differences in pain scores were observed after four weeks of active tDCS compared with sham (mean difference in average pain 0.03 (95% CI, -0.40 to 0.46; p = 0.89, mean difference in maximal pain 0.09 (95% CI, -0.42 to 0.60; p = 0.73). However, active tDCS reduced pain compared with baseline: Average pain (p = 0.026) and maximum pain (p = 0.012), unlike sham tDCS. However, taking all four weeks of treatment into consideration, sham tDCS reduced pain scores (p < 0.05). No differences were found between the treatments for the secondary outcomes. Responders to active tDCS showed increased temporal summation and lower pressure pain thresholds. CONCLUSIONS: Active tDCS significantly reduced pain compared with baseline but did not show an improvement over low-intensity sham tDCS. Responders to active tDCS exhibited features of central sensitization. Stimulation intensity may influence tDCS effectiveness. CLINICAL TRIAL REGISTRATION: The clinicaltrial.gov registration number for the study is NCT06152887.