Effect of metformin on serum level of vitamin B12 and folate in patients of type-2 diabetes mellitus

Background: Several types of DM are caused by a complex interaction of genetic and environmental factors. Depending on the etiology of the DM, factors contributing to hyperglycaemia include- reduced insulin secretion, decreased glucose utilization, and increased glucose production.Objective of the current study was to study the effect of metformin on the level of vitamin B12 and folate in patients of type 2 DM.Methods: This is hospital based study before and after metformin therapy randomized controlled trial was conducted in medicine ward of M. B. hospital, Udaipur. Baseline serum vitamin B12 and folate level of all patients were measured and treatment with metformin 500 mg twice a day was given for 6 months. After 6 months serum vitamin B12 and folate level of all patients were re-evaluated.Results: There was a significant positive correlation (r=0.824, p<0.001) between decrease in vitamin B12 and decrease in folate level after metformin treatment. When analysis for change in vitamin B12 is compared with change in MCV values after 6 months, negative correlation (r=-0.08, p>0.05) was obtained. A non significant correlation (r=-0.08, p>0.05) with change in level of serum folate and change in MCV values or haemoglobin level was obtained.Conclusions: Low serum vitamin B12 level is associated with longer duration and higher dose of metformin use. Routine determination of vitamin B12 level in patients with type 2 DM on high dose of metformin and those with prolonged use of metformin might help in identifying patients that would benefit from vitamin B12 supplements.