Lymphovenous Bypass as an Adjunct to Standard Care for Diabetic Peripheral Neuropathy: Protocol for a Randomized Assessor-Blinded Superiority Trial

Abstract Background Diabetic peripheral neuropathy (DPN) is a length-dependent, symmetric sensorimotor polyneuropathy with a substantial global and regional burden. Current pharmacologic options are largely symptomatic and do not modify the disease. Lymphovenous bypass (LVB), a supermicrosurgical procedure established for lymphedema, may modulate lymphatic-immune-microvascular dysfunction relevant to DPN. Objective The primary objective is to determine whether LVB combined with standard of care (SOC) improves small-fiber and autonomic function compared with SOC alone at 6 months. Secondary objectives are to evaluate the effects of LVB on large-fiber function, neuropathic pain, ulcer healing, quality of life, and relevant biomarkers, as well as to characterize the safety profile of LVB. Methods This is a SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials)–aligned, single-center, randomized, controlled, parallel-group superiority trial with a 2:1 allocation (LVB+SOC vs SOC alone). Randomization is stratified based on the presence or absence of active diabetic foot ulcers, as defined by the International Working Group on the Diabetic Foot and Infectious Diseases Society of America criteria. In total, 60 adults aged 20 to 80 years with confirmed DPN will be enrolled. LVB involves lymphatic-venous anastomosis to venules ≤0.8 mm. SOC consists of guideline-based glycemic and risk-factor management, pain control, and standardized wound care. Outcome assessors and statisticians are blinded. The primary outcomes are changes in clinical neuropathy burden and pain severity at 6 and 12 months. Secondary outcomes comprise objective measures of somatic and autonomic physiology, histopathological nerve fiber density, biological serum markers, and longitudinal ulcer epithelialization parameters. Data analysis will use mixed-effects models for repeated measures, with a sample size of 60 adults providing 80% power to detect a conservative between-group effect size of Cohen d =0.70. Results Recruitment commenced in February 2026 and is planned to continue through July 31, 2027, with follow-up through July 31, 2028. As of May 2026, we have enrolled 3 participants. The first participant has been treated, and a second participant is scheduled to undergo treatment. Data analysis and reporting are anticipated between late 2027 and early 2028. No outcome data are included. Conclusions This trial tests a mechanism-based, nonpharmacologic adjunct targeting lymphatic-immune-microvascular dysfunction in DPN. If effective, LVB could inform phenotype-directed treatment algorithms and motivate multicenter evaluation and health economic analyses.