Diabetes mellitus (DM) and chronic alcoholism (CA) are diseases that damage many organs and systems of the body and, in particular, lead to peripheral neuropathies. The pathogenesis of peripheral neuropathies caused by diabetes mellitus (DM) and CA is complex and diverse. Different types of peripheral neuropathies develop according to the leading pathogenetic mechanism. The most common type of peripheral neuropathy in DM is diabetic distal symmetric polyneuropathy (DSPN) and that in CA is alcoholic polyneuropathy (APN). The principles of diagnosis and treatment of DSPN and APN are considered. Treatment of DSPN and APN is complex, which is aimed at treating the underlying disease and includes non-drug and drug treatments. The mainstay of DSPN treatment is achievement of the optimal blood glucose level, maintenance of a healthy lifestyle (diet, daily activity), and correction of cardiovascular comorbidities (if any) with symptomatic pharmacotherapy for neuropathic pain (if any) with antidepressants or anticonvulsants. Antioxidants, such as B group vitamins (B1, B6 and B12) and alpha-lipoic acid (ALA), are widely used to treat DSPN in clinical practice. APN treatment involves cessation of alcohol consumption, physical and mental rehabilitation, and intake of B group vitamins (B1, B2, B6 and B12). The use of ALA in DSPN and APN is discussed.