Metformin is the only biguanide that is currently in use as an oral hypoglycemic in type II (noninsulin dependent) patients with diabetes. Like all hypoglycemic medications, metformin is not to be taken without careful analysis of associated risks. Lactic acidosis is the most studied and feared side effect; however, vitamin B12 (cobalamin) malabsorption is an underappreciated side effect in up to 30% of patients on metformin (Glucophage Label and Approval History. US Food and Drug Administration. Accessed October 1, 2008). The goal of this article is to examine the role of metformin in cobalamin deficiency, as well as outline the steps that are necessary to assess the incidence of B12 deficiency and its potential reversal with calcium supplementation in a clinical setting.
*4th-yr Medical Student, the University of New England, Biddeford, ME.
Chief Editor's Note: This article is the 2nd of 18 that will be published in 2010 for which a total of up to 18 AMA PRA Category 1 Credits™ can be earned. Instructions for how credits can be earned precede the CME Examination at the back of this issue.
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