Aims/Introduction: Diabetic peripheral neuropathic pain (DPNP) affects the functionality, mood and sleep patterns of patients with diabetes. Mirogabalin, an a 2 d ligand with a slower dissociation for a 2 d-1 versus a 2 d-2 subunits, showed efficacy and safety in a randomized, double-blind, placebo-controlled, 14-week study in Asian patients with DPNP. This open-label extension study evaluated the long-term safety and efficacy of mirogabalin in Asian patients with DPNP. Material and Methods: This 52-week open-label extension study was carried out in Japan, Korea and Taiwan in patients with DPNP. Patients received mirogabalin, initiated at 5 mg twice daily and increased to a flexible maintenance dosage of 10 or 15 mg twice daily. Adverse events were monitored throughout the study. Patients provided a selfassessment of pain using the Short-Form McGill Pain Questionnaire. Results: Of the 214 patients who entered the study, 172 (80.4%) completed the extension study. Of 172 patients who completed the study, 149 received the highest dosage of mirogabalin (15 mg twice daily). The most common treatment-emergent adverse events were nasopharyngitis, diabetic retinopathy, peripheral edema, somnolence, diarrhea, increased weight and dizziness. Most treatment-emergent adverse events were mild or moderate in severity. The incidence of treatment-emergent adverse events leading to treatment discontinuation was 13.1%. The visual analog scale and all other Short-Form McGill Pain Questionnaire subscales (sensory score, affective score, total score and present pain intensity) generally decreased over time from baseline until week 52. Conclusions: This extension study showed the safety and efficacy of a long-term flexible dosing regimen of mirogabalin 10 or 15 mg twice daily in patients with DPNP.