Iron and Diabetes Revisited

Iron is the most abundant transitional metal in the body. It has long been recognized that iron overload can increase the risk of diabetes, particularly in iron-overload states such as hemochromatosis and recurrent transfusions in diseases like thalassemia. Furthermore, a large body of epidemiological evidence suggests that an increase in dietary iron (as heme, mainly from meat and meat products) is associated with an increased risk of diabetes (1). In contrast, iron deficiency (over time one of the most common nutritional deficiencies in the world) may lower the risk of diabetes. Indeed, it has been suggested that recurrent phlebotomy may protect against diabetes (2), although there are no large multicenter, randomized controlled trials to support this hypothesis. In addition, iron has been implicated in the pathogenesis of renal disease including diabetic nephropathy (1). Two articles in this issue of Diabetes Care add to this evidence and report that prepregnancy dietary heme iron intake is associated with an increased risk of diabetes. The association remains significant even after adjustment for a variety of factors known to be associated with gestational diabetes mellitus (GDM). Bowers et al. (3) studied participants in the Nurses' Health Study which has a robust dataset and fairly reliable information on …