Does Metformin Treatment in Pediatric Population Cause Vitamin B12 Deficiency?

BACKGROUND/AIM: There have been no studies to date examining the effect of metformin treatment on vitamin B12 status in children and adolescents. In this prospective study, the effects of metformin on blood vitamin B12, serum methylmalonic acid (MMA), homocysteine and holo-transcobalamin-II (holo-TC-II) levels were assessed in pediatric age group.

MATERIALS AND METHODS: This prospective study was conducted at the Pediatric Endocrinology and Adolescent Department between January 2017 and March 2019. Metabolic syndrome and polycystic ovary syndrome diagnosed patients with insulin resistance and/or impaired glucose tolerance, patients with type 2 diabetes mellitus (DM) treated with metformin were enrolled in study. Blood vitamin B12, MMA, homocysteine, holo-TC-II levels and hemogram values were evaluated.

RESULTS: Twenty-four patients were enrolled in study. Among these, 15 (62.5%) were female. The mean age of patients was 13.7±2.3 (10-19) years. Sixteen patients were diagnosed with metabolic syndrome and 8 patients were type 2 DM. At 6-month follow-up of all patients, there was no statistically significant difference in terms of vitamin B12, homocysteine, MMA and holo-TC-II levels. A 0.6% decline in vitamin B12 levels were revealed. At 12-month follow-up of 11 patients (45.8%) (6 Type 2 DM, 5 metabolic syndrome), no statistically significant difference was determined in vitamin B12, homocysteine, MMA and holo-TC-II levels. There were 6% decline in vitamin B12 levels and 10.9% increase in homocysteine levels, 5.4% decrease was detected in holo-TC-II level.

CONCLUSION: Although no significant changes in the serum vitamin B12, homocysteine, MMA or holo-TC-II levels with metformin therapy were detected, long-term prospective studies with high-dose metformin treatment in pediatric population are needed to confirm our results.