Diabetic peripheral neuropathy (DPN) is the most common complication of type 2 diabetes mellitus (T2DM) and is associated with substantial morbidity, mortality, and healthcare costs. Vitamin B-12 plays a critical role in nerve protection and regeneration. However, clinical evidence regarding the effectiveness and optimal dose of vitamin B-12 supplementation for managing DPN in individuals with low serum vitamin B-12 levels remains inconclusive.

The aim of this study is to compare the effects of 2 different daily doses of oral vitamin B-12 supplementation on neuropathic parameters in patients with DPN and low serum vitamin B-12.

This 16 wk, randomized controlled trial enrolled adults with T2DM, DPN, and low serum vitamin B12 levels (<200 pg/mL). Patients were randomly assigned (1:1) to receive either 1000 μg or 2000 μg of oral vitamin B12 (methylcobalamin) daily. The primary outcomes were changes in neuropathic parameters, assessed by the numerical rating scale (NRS), Michigan neuropathy screening instrument examination (MNSIE), and neuropathy disability score (NDS). Secondary outcomes included serum B-12 levels and metabolic parameters.