Aims To determine the effect of a lifestyle intervention on serum transferrin and ferritin levels and the relationship between changes in transferrin and ferritin and changes in glucose tolerance and insulin resistance. Methods Randomized controlled lifestyle intervention directed at a healthy diet and increased physical activity in subjects with impaired glucose tolerance. Results After 1 year, the change in ferritin levels in the intervention group as compared with the control group did not reach statistical significance (P = 0.06). Transferrin change was independently related to the change in homeostasis model assessment of insulin resistance and ferritin change was related to the change in 2-h free fatty acids. Conclusions Changes in insulin sensitivity and postprandial lipid metabolism are related to changes in iron metabolism. AD - Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), University of Maastricht, Maastricht, The Netherlands.