Diabetes Drug Metformin Linked to Vitamin B 12 Deficiency


Diabetics treated over long periods with the drug metformin, one of the most commonly prescribed drugs for the treatment of diabetes, are at risk of developing vitamin B12 deficiency.  This condition is likely to get worse over time, according to a study published in the British Medical Journal.

Symptoms of Vitamin B12 deficiency, like fatigue, could be misdiagnosed as diabetic complications, but a simple blood test to check B12 levels could revel whether levels are low.  Vitamin B12 is found in meat, dairy products, eggs, fish, and can also be taken as a supplement.  It is necessary to maintain healthy nerve cells and red blood cells.

The  study out of Maastricht University Medical Center in the Netherlands followed 390 patients with type 2 diabetes, giving metformin to 196 of them three times a day for more than four years, and a placebo to the other 194.

The results showed that people who had taken metformin had a 19 percent reduction in their vitamin B12 levels compared with people who had taken a placebo.  Those taking the placebo had almost no change in vitamin B12 levels.  The reduced levels of vitamin B12 in the metformin group also persisted and became more apparent over time.

The data from this study provides a strong case for routine assessment of vitamin B12 levels during long term treatment with metformin.


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