Iron: how much is too much?

Gross iron overload has long been known to result in diabetes mellitus. However, it is now thought that milder levels of iron overload, possibly within the normal range, also increase the risk of diabetes mellitus. The article by Rawal et al in this issue ( Diabetologia doi: 10.1007/s00125-016-4149-3 ) provides further support for the relationship between mild degrees of iron overload and the risk of gestational diabetes. The purpose of this commentary is to briefly discuss the background of this relationship and the implications it may have for routine pregnancy care.