Abstract
Background: Metformin is widely used as first-line therapy for type 2 diabetes mellitus; however, long-term use is associated with reduced vitamin B12 absorption, which may contribute to or worsen peripheral neuropathy. Vitamin B12 supplementation has been proposed as a strategy to prevent or improve metformin-associated neuropathy.
Objectives: To compare the effectiveness of metformin alone versus metformin plus vitamin B12 supplementation in reducing neuropathy among patients with type 2 diabetes mellitus.
Study Design & Setting: This was a comparative, randomized study conducted over six months in the Department of Medicine Sheikh Zayed Hospital, Lahore from Jan 2025 to June 2025.
Methodology: A total of 120 patients with type 2 diabetes mellitus and features of peripheral neuropathy were enrolled and randomly divided into two groups of 60 each. Group A received metformin alone, while Group B received metformin plus oral vitamin B12 supplementation (1500 mcg daily) for 12 weeks. Neuropathy severity was assessed using the Michigan Neuropathy Screening Instrument (MNSI) at baseline and at 12 weeks. Serum vitamin B12 levels were measured at both time points. Data were analyzed using SPSS version 25, and a p-value ≤ 0.05 was considered statistically significant.
Results: Baseline characteristics were similar between the two groups. At 12 weeks, Group B showed a substantial increase in serum vitamin B12 levels, whereas Group A showed a slight decline. Neuropathy improvement was greater in Group B, with a larger reduction in MNSI scores compared to Group A. The proportion of patients with persistent neuropathy was lower in the vitamin B12–supplemented group.
Conclusion: The combination of metformin and vitamin B12 was more effective than metformin alone in improving neuropathy and restoring serum vitamin B12 levels in patients receiving long-term metformin therapy.