High iron levels may signal diabetes risk
Feb. 11, 2004

Based CHICAGO (AP) -- Women with high levels of iron in their blood may run nearly triple the risk of developing diabetes, a study found.

The research involved 32,826 healthy women who were followed for 10 years after giving blood samples. Type 2 diabetes was diagnosed in 698 of the women. On average, they who had significantly higher initial iron levels than the other women.

If the results are confirmed in further studies, simple blood tests might some day help doctors determine which patients will develop diabetes.

High levels might also indicate, for example, which women should avoid iron supplements, said co-author Dr. JoAnn Manson, chief of preventive medicine at Harvard's Brigham and Women's Hospital.

The findings appear in Wednesday's Journal of the American Medical Association.

It is known that people with hemochromatosis -- an inherited disease that causes the body to absorb too much iron from food -- are prone to diabetes.

Elevated iron levels can damage cells and interfere with the functioning of the organs, which may affect the body's use of insulin, a hormone that helps convert sugar in the blood into energy, the researchers said. Diabetes develops when the body doesn't make enough insulin or cannot use it properly.

Iron is necessary for red blood cell production. High levels may be hereditary or, some data have suggested, caused by consuming large amounts of iron-rich foods or high-dose iron pills.

In the current study, dietary iron was not strongly associated with high blood levels of iron, and the results are too preliminary to recommend any lifestyle changes, Manson said.

The researchers studied blood levels of ferritin, a protein that reflects the amount of iron in the body. Normal ferritin levels in women range from 12 to 150 nanograms per millilitre. Average levels were 109 in the women who developed diabetes, compared with 71.5 for the others.

Women in the group with the highest levels -- at least 102.2 -- were nearly three times more likely to develop diabetes than women in the group with the lowest levels, or less than 21.1.

Dr. David Baldwin, director of endocrinology at Rush University Medical Center, called the study inconclusive. He noted that many women with the highest iron levels were still within what is considered a normal range.

Baldwin said routinely testing iron levels would be hard to justify since doctors do not know which "normal" levels might be risky.

A previous study found high iron levels in people who had already developed diabetes, but they were thought to reflect inflammation that can occur with diabetes.

Baldwin said he suspects that is the case with the current study, though the researchers said they took inflammation into consideration.