Metformin Use and Vitamin B12 Deficiency: Untangling the Association.
BACKGROUND
Current evidence linking vitamin B12 deficiency with metformin use is inconsistent. Hence, there is uncertainty regarding the diagnostic approach in this scenario. Furthermore, this possible association has not been studied in the complete spectrum of patients with diabetes.


MATERIALS AND METHODS
We conducted a cross-sectional, controlled study with the objective of assessing differences in serum vitamin B12 levels among patients with and without diabetes with different metformin-treatment regimens. A total of 150 participants were recruited: patients with diabetes (group 1: metformin alone ≥850mg/day, group 2: patients with type 2 diabetes naive to treatment and group 3: metformin ≥850mg/day, in addition to any other oral glucose lowering agent or insulin, or both) and without diabetes (group 4: polycystic ovary syndrome or group 5: healthy individuals). Serum vitamin B12, folate levels and complete blood counts were obtained for the entire population. Methylmalonic acid and homocysteine were obtained for patients when vitamin B12 levels were found to be borderline or low.


RESULTS
When patients with or without diabetes were compared, no significant difference was found in relation to their vitamin B12 levels (517.62 versus 433.83; P = 0.072). No difference in vitamin B12 levels was found among participants with metformin use and metformin naive participants (503.4 versus 462.3; P = 0.380).


CONCLUSIONS
Irrespective of metformin use, no significant difference in the serum levels of vitamin B12 was observed, both in patients with and without diabetes. In the light of the body of evidence and the results of this study, a universal recommendation for vitamin B12 deficiency screening cannot be made.
['Rodríguez-Gutiérrez|René|R|', 'Montes-Villarreal|Juan|J|', 'Rodríguez-Velver|Karla Victoria|KV|', 'González-Velázquez|Camilo|C|', 'Salcido-Montenegro|Alejandro|A|', 'Elizondo-Plazas|Anasofia|A|', 'González-González|José Gerardo|JG|']
D000293:Adolescent D000328:Adult D000368:Aged D003430:Cross-Sectional Studies D003924:Diabetes Mellitus, Type 2 D005260:Female D006801:Humans D007004:Hypoglycemic Agents D008297:Male D008687:Metformin D008875:Middle Aged D014805:Vitamin B 12 D014806:Vitamin B 12 Deficiency D055815:Young Adult
Metformin Vitamin B12 deficiency Type 2 diabetes Cyanocobalamin-deficiency