Background & Objectives: With respect to the importance of diabetes mellitus prevalence and contradictory role of treatment with metformin on vitamin B12 and folic acid serum levels and this study was done in order to determine of Vitamin B12 and folic acid serum level in patients with diabetes mellitus under treatment with metformin. This research was performed in diabetes center of Kashan in 2004.

  Methods: Information about research method, target and conclusions were given to patients. Those who were under treatment with anti acids, and chemotherapy drugs and also those who were alcoholic and had gastrointestinal diseases and hepatic diseases were excluded among all samples of this research, then patients were divided in to 2 groups: The first group were under treatment with metformin, second group were with other drugs for diabetes treatment. All of people were under treatment for at least 6 months folic acid, vitamin B12 serum level of them were checked after 14 hours fasting and the findings were studied with SPSS software and X2 tests, T test fisher exact test.

  Results: there were 145 (84.31%) female and 27 male (15.69%) between 172 patients. Average age of patients was 52.1±12.7 years. Duration of disease was 5.42±9.1 and average Body Mass Index was 27.7±4.7 kg/m2. Folic acid average was 9.2±5.1 (ng/dl) in patients who consumed metformin and was 8.7±4.6 (ng/dl) in patients without consuming of metformin that did not show significant difference (p=0.557). B12 vitamin average was 5.43±342.54 (pg/dl) in patients under treatment with metformin and was 516±32.16 (pg/dl) in patients without consuming metformin in statistical findings between these 2 groups was not significant. (p=0.639). Significant correlation was observed between age of patients whom were studied and serum folic acid level of them. (p=0.07), But did not show significant correlation between age with serum B12 level (p=0.095). There was no significant correlation between age, length of disease, body mass index and level of B12 and folic acid.

  Conclusion: Correlation between reduction serum level of B12 and folic acid with consuming of metformin was not found. Difference between results of this study with other studies is likely because of more use of routine vitamin supplement that is consumed by patients without physician’s recommending, genetic differences or drugs composition.