Assessment of Serum Vitamin B(12) and Folate Levels and Macrocytosis in Patients with Type 2 Diabetes Mellitus on Metformin Attending Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia: A Cross-Sectional Study

BACKGROUND: Metformin is the first-line drug in the treatment of type 2 diabetes mellitus. Monitoring vitamin B(12) deficiency associated with long-term and high-dose therapy is not a common practice in many clinical settings in Ethiopia. OBJECTIVE: The study aimed to measure levels of serum vitamin B(12) and folate and to assess the macrocytic status of type 2 diabetes mellitus patients on metformin. METHODS: A cross-sectional study was conducted on 80 type 2 diabetes mellitus patients who had been on metformin for 5 months or more at the diabetic clinic of Tikur Anbessa Specialized Teaching Hospital. Serum vitamin B(12) and folate levels were quantified by chemiluminescent immunoassays. Mean corpuscular volume was determined by complete blood count. Differences in vitamin B(12) and folate levels and mean corpuscular volume between different groups were assessed using Kruskal–Wallis H and Mann–Whitney U tests. RESULTS: Vitamin B(12) and folate deficiency were documented in 5% and 23.8% of participants, respectively, and 6.2% of patients were macrocytic. Levels of vitamin B(12) and folate in patients who had been on metformin >1,500 mg/day ≥4 years were significantly lower those who had been on metformin 1,000–1,500 mg/day and <1,000 mg/day <4 years, respectively. CONCLUSION: Low serum vitamin B(12) and folate levels and macrocytosis were found to be associated with prolonged metformin treatment.