Metformin for type 2 diabetes January 2019
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* Robert S. Moskowitz

**TO THE EDITOR**: I enjoyed reading “Should metformin be used in every patient with type 2 diabetes” by Makin and Lansang in the January 2019 issue.1

I just wanted to point out that metformin is a frequent cause of low serum vitamin B12 levels, and serum vitamin B12 levels should be monitored intermittently in patients using metformin.

*   Copyright © 2019 The Cleveland Clinic Foundation. All Rights Reserved.

## REFERENCE

1.  Makin V, Lansang MC. Should metformin be used in every patient with type 2 diabetes? Cleve Clin J Med 2019; 86(1):17–20. doi:10.3949/ccjm.86a.18039
    
    [FREE Full Text](http://www.ccjm.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiRlVMTCI7czoxMToiam91cm5hbENvZGUiO3M6NToiY2Nqb20iO3M6NToicmVzaWQiO3M6NzoiODYvMS8xNyI7czo0OiJhdG9tIjtzOjIyOiIvY2Nqb20vODYvNC8yMzcuMS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=)