Prevalence of Vitamin B12 Deficiency in Type 2 Diabetes Mellitus Patients on Metformin

Abstract

Background: Diabetes Mellitus is the commonest endocrine disease and metformin is the commonest oral anti diabetic agent prescribed. B12 deficiency is one of the side effects of metformin due to the effect on calcium-dependent membrane action in the terminal ileum leading to malabsorption of vitamin B12. Aim of study: for determination of the prevalence and association of Vitamin B12 deficiency in patients with type 2 diabetes mellitus managed with metformin. Methods: This case control study took place in the department of medicine, Alhussein teaching hospital in Nassiriyah city in Iraq .We selected 43 patients with type 2 diabetes mellitus on metformin for at least 12 months and 42 patients were taken as control. Patients with vitamin B12 levels of less than 297 pg/mL or methyl malonic acid (MMA) more than 47 ng/mL were considered B12 deficient. Results: serum B12 level was low in 17 out of 43 patients (39.5%) among cases, and 8 out of 42 patients (19%) among controls . Mean age was 50 (±12.86) years in the control and 52 (±12.12) years in the case group. Control group composed of 23 males and 19 females, while case group composed of 17 males and 26 females. Duration of DM was 5.1 (±4.5) years for control and 6.1 (±3.75) years for cases. HbA1c % was 8.44 (±2) for control and 8.25 (±1.65) for case . Vitamin B12 level was 349 (±99) pg/ml for control and 343 (±124) pg/ml for cases. B12 deficiency correlated significantly with the duration and dose of metformin with (P.value=0.001and 0.002) respectively. Conclusion: we found that there was a high prevalence of vitamin B12 deficiency among patients managed on metformin with significant effect of duration and dose of metformin use on B12 levels. This should be considered in patients treated with metformin.