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A commonly prescribed Type 2 diabetes drug has been linked to vitamin B12 deficiency.
The vitamin helps the body form red blood cells and maintain healthy neurological function.
It is typically found in meat, fish and dairy including red meats, salmon, cod, milk, cheese and eggs.
Those with a B12 deficiency can suffer problems including fatigue and anaemia, which could easily be misdiagnosed as being due to diabetes, its complications or ageing.
A total of 390 people took part in the research. Half the group took 850mg of metformin three times a day for 4.3 years on average, and the results were compared with the other half taking a dummy (placebo) drug.
The authors said: “Our study shows that it is reasonable to assume harm will eventually occur in some patients with metformin-induced low vitamin B12 levels.
“Current guidelines indicate that metformin is a cornerstone in the treatment of Type 2 diabetes, but make no recommendations on the detection and prevention of vitamin B12 deficiency during treatment.
Copyright Press Association 2010
British Medical Journal