Evaluation of effect of dose and duration of treatment with metformin on serum vitamin B12 levels in type 2 diabetic patients
K P Harsha1, G Niveditha2, Reddy Sanjay2, K M Prasanna Kumar2 & M C Shivamurthy2
Introduction: Metformin induced impaired vitamin B12 absorption leading to fall in serum cobalamin levels has been described in literature as early as 1971. Approximately 10% of patients and in some studies 30% of patients on metformin therapy developed metformin related cobalamin deficiency. The risk of cobalamin deficiency is comparatively more among patients with vegetarian diet than in non-vegetarians.
Objective: To evaluate the effect of dose and duration of treatment with metformin on serum vitamin B12 levels in type 2 diabetic patients.
Materials and methods: A total of 40 patients ON metformin therapy were chosen. By using a pilot tested pro forma details were collected on demographic data, dietary habits. Duration of treatment with metformin and dose of metformin was also noted. 5 ml of blood will be collected and sent to the central laboratory for serum vitamin B12 estimation. Vitamin B12 estimation was done using a recently developed method called as active vitamin B12 assay.
Results: Our results showed that mean vitamin B12 levels among patients on dose of <1 g/day was 57.8 Pmol/dl and was 40.4 Pmol/l (picomoles/liter) in patients on dose more than 1 g/day. The mean B12 levels were 39.7, 54.3 and 75.9 Pmol/l in duration of treatments <2, 35 and >5 years respectively.
Conclusion: Our study shows that dose and duration of metformin did not show any significant relationship with serum vitamin B12 levels.