Pregabalin and Alpha-lipoic Acid Combination Versus Each Monotherapy in Patients With Diabetic Peripheral Neuropathy

Inclusion Criteria: * aged 19 to 75 * type 2 diabetes mellitus with HbA1c (Hemoglobin A1c) ≤ 10 % * peripheral (eg. hands, feet) neuropathic pain (eg. abnormal sensations, numbness, pain, etc.) within 3 months (12 weeks) * diagnosed with diabetic peripheral neuropathy (DPN) * VAS pain score ≥ 40 mm * written informed consent Exclusion Criteria: * brittle diabetes mellitus * ALT (Alanine Transaminase), AST (Aspartate Transaminase), CPK (Creatine Phosphokinase) level ≥ 3 times the upper limit of normal (UNL) or active liver disease * severe renal impairment (eGFR (estimated glomerular filtration rate) \< 60 mL/min/ 1.73m2) * treated with antiepileptic drugs within 1 week at randomization * other nervous system or neuropathic disorders that may affect pain evaluation * oral drug administration is not possible, or hypersensitive or allergic to pregabalin, r-thioctic acid tromethamine, thioctic acid, and other excipients * pregnant, lactating, or childbearing potential * alcoholics, drug abusers, and patients who are difficult to participate in clinical trials due to psychological and emotional problems * have participated in other clinical trials within 30 days at screening