A Multicenter, Prospective, Observational, and Single-Arm Interventional Study of Mirogabalin in Diabetic Peripheral Neuropathic Pain: Rationale and Design of Dia-NeP

Background/Objectives: The exact prevalence of and recent changes in diabetic polyneuropathy (DPN) and diabetic peripheral neuropathic pain (DPNP) in Japan are unclear. The oral gabapentinoid, mirogabalin besylate (mirogabalin), is effective with a good safety profile for DPNP with moderate-to-severe pain (numerical rating scale [NRS] scores ≥ 4). However, clinical evidence for mild pain (NRS scores ≤ 3) is unclear. The Dia-NeP study aims to examine: (1) the prevalences of DPN and DPNP and background factors in patients with type 2 diabetes mellitus (T2DM); and (2) the efficacy and safety of mirogabalin in patients with DPNP, including those with mild pain.
Methods: The Dia-NeP study is a multicenter, prospective study consisting of two parts, a baseline survey and an interventional study, to be conducted from March 2025 to August 2026 in patients with T2DM in Japan. The baseline survey is the observational study investigating the epidemiology of DPN and DPNP, and the interventional study is an exploratory, single-arm, open-label study of 12-week mirogabalin treatment. Of patients with T2DM enrolled in the baseline survey, those diagnosed with DPNP who have an NRS score for pain ≥ 1 will be included in the interventional study. The target sample size is 1000 to 3000 patients for the baseline survey and 100 for the interventional study.
Planned Outcomes: The primary endpoint is the change from baseline in the NRS score at week 12 in the interventional study. The safety endpoint is adverse events. This study will not only show the latest prevalence of DPN and DPNP in Japan, but is also the first study to investigate the efficacy and safety of mirogabalin in patients with DPNP having mild pain, as well as moderate-to-severe pain, and is expected to provide useful evidence for future DPN and DPNP treatment.
Trial Registration: Japan Registry of Clinical Trials (jRCTs031240623, registered 20/January/2025, https://jrct.mhlw.go.jp/en-latest-detail/jRCTs031240623).