Association between vitamin B12 deficiency and clinical Peripheral Neuropathy in type 2 diabetic patients on Metformin therapy in the outpatient clinics of Ain Shams University Hospitals, Egypt

Abstract

Background: Vitamin B12 malabsorption is one of the side effects of long-term Metformin intake. Prolonged vitamin B12 deficiency can lead to irreversible nervous system damage. The current study aimed to determine the association between serum vitamin B12 level and clinical Peripheral Neuropathy among T2DM patients who are on Metformin in comparison to those not taking it. Methods: A cross-sectional study conducted in Egypt and recruited 100 type 2 diabetic patients who were divided into 2 groups; metformin treated, and non-metformin treated (50 subjects per group). The collected data included personal history, medical history, dietetic history that included frequency of eating food rich in vitamin B12 and clinical Peripheral Neuropathy assessment by Toronto Clinical Scoring System (TCSS). Blood samples were collected for assessment of HbA1c and vitamin B12 level. Results: Vitamin B12 deficiency was present in 4% of metformin group and 2% of non- metformin group. The mean value of vitamin B12 was significantly lower in metformin users than non- metformin users (624.3 ±364.1 pg/ml and 991.0 ±489.9 pg/ml respectively), p= 0.023. The glycated haemoglobin level was significantly higher in non-metformin users than metformin users (p value= 0.03). Peripheral Neuropathy was significantly associated with HbA1c (p value= 0.04) and female gender (p value= 0.001). Conclusion: Vitamin B12 level was lower in type 2 diabetic patients on metformin compared to those on other oral antidiabetic drugs, but without significant deficiency. Peripheral Neuropathy was significantly associated with poor glycaemic control and female gender but was not associated with vitamin B12 deficiency