Metformin – Is This First Line Medicine Safe?

This is the substance of an article published in the April issue of Diabetes Care. The title they use is “Diabetes Prevention With Metformin Is Safe, Well-Tolerated.” In essence this is correct, but only when other vital information is added which is absent from the details of this study. A pharmacist friend very kindly pointed this out to me in an email.

She stated, “Metformin can for many (but not all) individuals cause a Vitamin B12 deficiency. Unless they consume foods high in Vitamin B12, most people will end up having this deficiency in long-term Metformin use.” Even my own endocrinologist suggested adding a Vitamin B12 supplement to my regimen while on Metformin. I am thankful I listened to her. I was not Vitamin B12 deficient, but I was at the low point in the recommended range.

Based on my experience, I would suggest anyone taking Metformin (glucophage) talk with their doctor about having the Vitamin B12 test done to establish a baseline and a discussion about adding Vitamin B12 at some point. I repeat, this should include anyone taking or adding metformin to their medication regimen. This is one area that I now feel strongly enough about to repeatedly urge people taking metformin to have the vitamin B12 test done. 

A little background into the symptoms of vitamin B12 deficiency shows they are the classic fatigue and anemia. Most doctors will not do this test, “because the 'Standard of Care' is to ONLY do Vitamin B12 Testing if a patient has a condition called Macrocytic Anemia- where red blood cells become large and shows up as a high number on the MCV Blood Test that is part of a Complete Blood Count. This is somewhat arbitrary and stops many tests that could prevent severe vitamin B12 deficiency.

This article from WebMD dated June 8, 2009 is the article my pharmacist friend suggested that I read. Yes, it is a very convincing argument for being screened for vitamin B12 deficiency. In the study, 40 percent of type 2 diabetes patients using metformin had vitamin B12 deficiency or were in the low-normal range for vitamin B12. Of 77 percent of metformin users with vitamin B12 deficiency also had peripheral neuropathy. This is a common nerve damage complication associated with type 2 diabetes.

Peripheral neuropathy is a major complication of diabetes, as such, the researchers suggest that people using metformin be screened for vitamin B12 deficiency or supplemented with vitamin B12. They further stated that anyone already diagnosed with peripheral neuropathy that uses metformin should be screened for vitamin B12 deficiency.