Abstract

Metformin treatment, both duration and dose, is associated with increased risk of vitamin B12 (B12) deficiency. B12 deficiency causes Hyperhomocysteinemia (HHcy), which is associated with an increased risk of a variety of diabetic co-morbidities. As a result, the newest "Standards of Medical Care in Diabetes-2017", issued by the American Diabetes Association included a recommendation to periodically assess B12 status and, as needed, utilize B12 replacement therapy among diabetes patients receiving metformin. Routine screening, using appropriate B12 assessment methods and interpretation, would enable providers to identify individuals with low B12 levels at an early stage. Prompt treatment with B12 injections or oral supplements may help in reducing the risk of low B12- and HHcy-related sequelae and their associate medical cost. The assessment of B12 status and interpretation of results is not straightforward since several B12 assessment measures are available, including serum/plasma B12, Mean Corpuscular Volume, Homocysteine, Holotranscobalamin II and Methylmalonic Acid. The goal of this manuscript is to 1) Describe available B12 assessment methods including their advantages and disadvantages, 2) Interpret laboratory results of B12 biomarkers, and 3) Discuss available B12 deficiency treatment options. Routine screening, when appropriate B12 status analyses are performed and interpreted, would enable physicians to identify individuals with low B12 at early stage. Treatment with B12 injections or supplements would help in reducing risk of low B12 and HHcy-related symptoms. Such practice would reduce pain and suffering of diabetic patients. It would also decrease medical cost associated with treatments of diabetic co-morbidities.

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