If cardiovascular disease is one point in iron’s web of disease, diabetes may be another.
The first hint of a relationship between iron and diabetes came in the late 1980s, when researchers discovered that patients receiving regular blood transfusions (which contain quite a bit of iron) were at significantly increased risk of diabetes. In hemochromatosis, there had been no way to know if the associated disturbance in glucose metabolism was due to the accumulation of iron itself, or to the underlying genetic defect. This new link between frequent transfusions and diabetes was indirect evidence that the iron itself may be the cause.
The next step was to mine existing data for associations between markers of iron status and diabetes. The first study to do so came out of Finland in 1997: Among 1,000 randomly selected Scandinavian men, ferritin emerged as a strong predictor of dysfunctional glucose metabolism, second only to body mass index as a risk factor. In 1999, researchers found that an elevated ferritin level increased the odds of having diabetes fivefold in men and nearly fourfold in women—similar in magnitude to the association between obesity and diabetes.
Five years later, another study found that elevated ferritin roughly doubled the risk for metabolic syndrome, a condition that often leads to diabetes, hypertension, liver disease, and cardiovascular disease.
