In our country, alpha-lipoic acid is widely used as a pathogenetic therapy for diabetic polyneuropathy (DPN). Objective: to compare the efficiency and safety of using oral and injectable α-lipoic acid for DPN. Patients and methods. The investigation enrolled 47 patients with a verified diagnosis of DPN, who were divided into two groups. Group 1 included 23 patients (10 men and 13 women; mean age, 62.9±7.5 years), Group 2 consisted of 24 patients (9 men and 15 women, mean age, 65.5±7.9 years). All the patients used Berlithione: Group 1 received its intravenous doses of 600 mg for 14 days, then oral ones of 600 mg for other 16 days; Group 2 took oral doses of 600 mg for 30 days. The therapy results were assessed using the digital rating scale (DRS), the Douleur Neuropathique 4 (DN4) neuropathic pain rating scale, and the neurological soft signs (NSS), and electroneuromyography (ENMG) data. Results and discussion. Berlithione was found to have a good tolerability. No adverse reactions were detected in any case; and there was no need to discontinue this drug. On day 21 of therapy, there were statistically significant differences in the indicators of pain intensity on DRS in Group 1 patients (p1 month) for DPN.