Vitamin B12 Deficiency in Diabetic Patients on Metformin Therapy: A cross-sectional study from Oman

OBJECTIVES: This study aimed to determine the prevalence of vitamin B12 deficiency amongst diabetic patients on metformin therapy. METHODS: This cross-sectional study was conducted at general clinics at the University Health Center and diabetes outpatient clinics at Sultan Qaboos University Hospital, Muscat, Oman, between January and December 2017. All Omani adults who were diagnosed with type 2 diabetes mellitus and took metformin were invited to participate in the study. The variables included in this study were age, gender, duration of diabetes, dose and duration of metformin therapy, haemoglobin and glycosylated haemoglobin level. RESULTS: A total of 248 subjects were included (response rate = 95.4%) of which 26 (10.5%) were vitamin B12 deficient and 53 (21.4%) were borderline deficient. The mean daily dose of metformin was highest among vitamin B12 deficient group (1,981 ± 222 mg; P = 0.004). CONCLUSION: The prevalence of vitamin B12 deficiency is considerable among diabetic patients on metformin therapy. Further research is needed to confirm the need for routine screening and monitoring.