30-day and lasting impacts on utilizing a novel orthotic insole for tactile stimulation in diabetic peripheral neuropathy: a double-blind, randomized, sham-controlled trial

Background Diabetic peripheral neuropathy (DPN) can lead to diabetic foot ulceration (DFU) and disabilities. DPN also increases vibration perception threshold (VPT) and decreases tactile sensitivity. Applying a vibrating insole is an efficient way to decrease VPT and improve tactile sensibility. Objective To investigate the continuing and lasting effects of applying a novel vibrating orthotic insole (VOI) combined with a newly designed stimulus (a random 0–100 Hz square wave pulse signal integrated with pseudorandom white noise via a stochastic resonance approach) for tactile stimulation in DPN. Methods A randomized sham-controlled trial with a parallel design and a double-blind strategy was conducted in this study. Sixty-four mild-to-moderate DPN were randomized by a computer-generated algorithm into two interventions: 1) using the VOI mixed with the newly designed stimulus; 2) using the VOI with only 100 Hz frequency vibration. Each intervention was done at home for sixty minutes a day over thirty days. VPT outcomes were assessed on the 1st, 15th, and 30th days. Following up on the remaining effects of employing the VOI combined with the newly designed stimulus was performed after completing Intervention 1 by evaluating VPT values every seven days. Results Intervention 1 could significantly reduce VPT and effectively enhance tactile sensation ( P <0.001). In contrast, Intervention 2 considerably increased VPT. Follow-up, VPT was steady at the end of Intervention 1 for the first week before progressively rising over a month; after that, it rose until it exceeded baseline, which took approximately two to three months. Conclusions Utilizing the VOI in conjunction with a random 0–100 Hz square wave pulse signal and pseudorandom white noise via a stochastic resonance approach could offer lowering VPT, maintaining decreased VPT, and improving tactile sensitivity. The VOI may benefit neurorehabilitation in DPN, e.g., preventing DFU and its recurrence, restoring/prolonging tactile sensation, slowing DPN deterioration, and avoiding lower extremity amputation. Trial registration Thai Clinical Trials Registry: TCTR20230601001 (ThaiClinicalTrials.org).