The effects of oral iron supplements on insulin and glucose metabolism in women at high risk of diabetes

Swiss partners

• ETH Zürich: Nicole Stoffel (main applicant), Michael Zimmermann

Partners in the MENA region

• American University of Beirut, Lebanon: Omar Obeid (main applicant), Carla El-Mallah

Presentation of the projet

Background
Routine daily iron supplementation is recommended for all women during pregnancy and iron supplementation is also first line treatment for overweight women who are iron deficient. High dose iron supplementation in women acutely increases serum hepcidin. High serum hepcidin is linked to abnormalities in glucose and insulin metabolism and may reduce insulin sensitivity. Both pregnant women and overweight women are already at high risk of insulin resistance and impaired glucose tolerance (IGT). Whether their risk of IGT is further increased by the acute increase in serum hepcidin after high dose daily iron supplementation is unclear. If high dose daily iron supplementation decreases insulin sensitivity though acute increases in hepcidin, this would argue that these risk groups be given regimens of iron supplementation that do not acutely increase hepcidin, that is, lower dose, alternate day therapy.

Study aims
Our primary study aim is to assess whether high dose daily iron supplementation can impair glucose metabolism by decreasing insulin sensitivity in overweight women and pregnant women, two risk groups for IGT. A secondary aim is to assess whether the impairments in insulin and glucose metabolism are associated with higher hepcidin concentrations induced by high dose daily iron supplementation.

Study overview
The study will be a randomized, double-blind 17-day metabolic intervention trial including 14 days of high-dose or low-dose iron supplementation. The study will be done at the American University of Beirut (AUB). An identical design will be used in both pregnant women and OW women. The participants will undergo three oral glucose tolerance tests (OGTTs), one before beginning iron supplementation (day 0), one on the final day of supplementation (day 14) and one after supplementation has been stopped for three days (day 17).