Vitamin B12 levels in metformin-treated type 2 diabetes patients

Abstract

Background. Metformin is the most widely used oral antihyperglycaemic drug, but it may lower B12 status, which could have important clinical implications. There are limited data about the effect of metformin use on serum vitamin B12 levels in type 2 diabetes mellitus (DM) patients.Aim. To study serum Vitamin B12 levels in patients with type 2 diabetes mellitus who were receiving metformin and compared them to those never treated with metformin. Materials and methods. A total of 60 patients with type 2 DM (group 1, n = 35, receiving metformin and group 2, n = 25, never treated with metformin) from the endocrinology clinic in Chernivtsi were studied. Serum vitamin B12 levels were measured in all patients. Results and discussion. The serum vitamin B12 levels were 239.6 ± 37.4 pg/ml in metformin group and 293.6 ± 42.3 pg/ml in the no metformin group (p = 0.37). When adjusted for duration of DM, metformin use was associated with a 57.2 ± 7.3 pg/ml (p = 0.03) lower serum vitamin B12 levels. Serum vitamin B12 levels were higher by 41.4 pg/ml in patients with DM of 1—5 years compared to those with recently diagnosed diabetes (p = 0.41). Serum vitamin B12 levels were higher by 119.4 pg/ml in patients with duration of DM > 5 years compared to those with recently diagnosed diabetes (p < 0.02). Similarly, serum vitamin B12 levels were 77.1 pg/ml higher in > 5 years DM duration group compared to 1—5 year duration of DM group (p = 0.03). Serum vitamin B12 levels for the entire cohort were higher by 11.8 ± 1.7 pg/ml (p < 0.01) for every 1 year increase in the DM duration. Conclusions. Metformin use was associated with a lower serum vitamin B12 levels when adjusted for duration of DM. Increasing duration of DM was associated with higher serum vitamin B12 levels.