Diet can be a major cause of type 2 diabetes, as the report last week on trans fatty acids revealed. But high levels of iron can be another major cause, especially in women, a new study has confirmed.
Researchers at Harvard School of Public Health made the discovery after monitoring blood samples of 32,826 women. Of those, 698 went on to develop diabetes during the 10 years' follow-up period. After stripping out other risk factors such as diet, lifestyle and weight, the researchers found that all those who developed diabetes had high levels of iron.
There's quite a body of research that suggests just why iron, or ferritin concentrations, can cause diabetes. Iron can create free radicals, while iron deposits in muscles decreases glucose uptake, and affects insulin synthesis.
So how come some people get higher iron stores in their bodies? In large part, researchers believe, it can be down to a genetic defect, known as homozygous hereditary haemochromatosis, which allows more iron to be absorbed.
Iron levels are also increased when drinking alcohol, and one study found that it affects men as well as women.
(Source: Journal of the American Medical Association, 2004; 291: 711-17).