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Diabetics on Glucophage, Listen Up

WebMD Health News
Reviewed by Merle Diamond, MD

Sept. 15, 2000 -- Popping a calcium tablet might be an effective way for people with type 2 diabetes who take Glucophage to ensure that their vitamin B-12 levels stay where they should. While the common antidiabetes drug lowers blood sugar levels and makes insulin work better, the drawback is that it may also cause the important vitamin B-12 to work less effectively.

Nutrition expert Naomi K. Fukagawa, MD, PhD, tells WebMD, "Vitamin B-12 is important to the body in order to [break down] carbohydrates and fats, as well as amino acids. It also plays a key role in nervous system function and blood cell development. " Fukagawa is associate professor of medicine at the University of Vermont College of Medicine in Burlington.

The study holds a bad news-good news message. "Our study suggests strongly that individuals on a reduced calcium intake will develop a B-12 deficiency if prescribed Glucophage for type 2 diabetes," lead author William A. Bauman, MD, tells WebMD. But the report appears to offer a simple solution: Take a calcium tablet. The study findings were published in the September issue of the journal Diabetes Care. Bauman is professor of medicine at Mount Sinai School of Medicine in New York.

A total of 21 patients of similar age and ethnic backgrounds were included in the study at the diabetes clinic of the Veterans Affairs Medical Center in New York. Fourteen of the subjects were switched from their usual antidiabetes medication and given Glucophage.

Initially, vitamin B-12 levels were not significantly different between the two groups. But after three months, vitamin B-12 levels dropped in the group taking Glucophage. But when this group was given Tums tablets daily for one month, the decline in B-12 levels reversed.

According to Ralph Green, MD, who was not involved in the study, "The occurrence of B-12 deficiency is particularly important because preventable nerve damage caused by [this] deficiency may be mistaken for the [problems] that often occurs in diabetes." Green is professor and chair of the department of medical pathology at the School of Medicine, University of California-Davis, in Sacramento.

Bauman says patients with type 2 diabetes treated with Glucophage -- especially those who do not consume dairy products on a daily basis or do not take calcium supplements -- should increase their intake of calcium and should be closely monitored for vitamin B-12 deficiency. Taking a calcium tablet daily "is simple and important to do," he says.

Other causes of vitamin B-12 deficiency include special diets (for example a strict vegetarian diet excluding all meat, fish, dairy products, and eggs), chronic alcoholism, and Crohn's disease.

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