Investigation of the vitamin B12 deficiency with peripheral neuropathy in patients with type 2 diabetes mellitus treated using metformin

OBJECTIVE The relationship between vitamin B12 deficiency and peripheral neuropathy has been shown in a number of previous studies. Metformin is the indispensable first-line treatment for type 2 diabetes mellitus (DM) worldwide. One of the adverse effects of the use of metformin is vitamin B12 deficiency. In the present study, we investigated the relationship between vitamin B12 deficiency and peripheral neuropathy due to the use of metformin. METHODS Patient's laboratory and electromyography (EMG) data were retrospectively reviewed. Patients with no EMG report and other necessary information were excluded from the study. RESULTS Eighty-six patients with type 2 DM using metformin were included in the study. Of these patients, 26 were males and 60 were females. The mean age of the patients was 55.1±7.7 years. The mean body mass index of the patients was 29.1±9.01 kg/m2. The mean HbA1c level of the patients was 8.6%±2.1%. The mean duration of diabetes was 8.02±5.4 years. The incidence of vitamin B12 deficiency was 38.4%. Peripheral neuropathy was detected in 33.7% patients. There was no statistically significant difference in vitamin B12 levels between patients with peripheral neuropathy and those without peripheral neuropathy (p=0.64). CONCLUSION Therefore, it can be concluded that the lack of vitamin B12 secondary to the use of metformin did not significantly increase the frequency of peripheral neuropathy.