Vitamin B12 deficiency in patients with type 2 diabetes mellitus using metformin and the associated factors in Saudi Arabia

OBJECTIVES: To assess the presence of vitamin B12 deficiency among metformin users and associated factors in patients with type 2 diabetes mellitus. METHODS: An observational cross-sectional study was conducted with 307 diabetic patients in the primary health care centers at King Abdulaziz Medical City (KAMC), Riyadh, Saudi Arabia between October 2017 and January 2018. Face-to-face interviews were conducted with the participants, using a designed checklist. RESULTS: The prevalence of vitamin B12 deficiency was (3.6%) and the majority of the sample had borderline B12 levels (66.1%). The vitamin B12 deficiency and borderline levels were strongly associated with the dose of metformin. Patients taking doses of metformin more than 1000 mg had lower levels of vitamin B12. The use of multivitamin and vitamin B complex was assessed, and it was found that there was a marked decrease in the prevalence of vitamin B12 deficiency in patients using vitamin B complex containing more than 200 mcg vitamin B12. CONCLUSION: Our findings show a low prevalence of vitamin B12 deficiency in type 2 diabetic patients taking metformin. The majority of the sample had borderline deficiency; therefore, additional investigation and management are required.