Metformin, a drug in common use for diabetes, may cause vitamin B12 deficiency which might become worse over time. Coen Stehouwer of Maastricht University Medical Center in the Netherlands led a team of researchers in a study of 390 patients who had type 2 diabetes. The patients were followed for over four years.
Volunteers who took the drug Metformin experienced a drop of 19 percent in their levels of vitamin B12. Those who took the placebo did not have a similar drop. Vitamin B12 deficiency causes anemia, fatigue, cognitive changes and nerve damage.
"Vitamin B12 is essential to maintain healthy nerve cells and red blood cells. It is found in meat, dairy products, eggs, fish, shellfish and fortified breakfast cereals, and it also can be taken as a supplement."
Stehouwer recommends close monitoring of the levels of vitamin B12 for any patients with type 2 diabetes who are taking the drug Metformin for long term treatment.