Serum ferritin concentration in gestational diabetes mellitus and risk of subsequent development of early postpartum diabetes mellitus

Purpose: To compare the serum ferritin concentrations of normal pregnant women with those having gestational diabetes mellitus (GDM) and to determine the possible role of ferritin in predicting pregnancy outcome and early development of postpartum glucose intolerance and diabetes mellitus. Method: This case-control study consisted of 128 pregnant women (64 women with GDM and 64 age-matched healthy pregnant women) seen at a university hospital in Zanjan, Iran. Anthropometric measurements were determined, and serum ferritin, C-reactive protein, insulin, glycosylated hemoglobin (HbA 1c), and hemoglobin levels were measured. Pregnancy outcomes were recorded in all subjects. In the women with GDM, a diagnostic oral glucose tolerance test was performed eight weeks after delivery. Results: Women with GDM had a higher concentration of serum ferritin (112 +/- 28.4 pmol/L in GDM versus 65 +/- 16.9 pmol/L in controls, P < 0.001). A positive correlation was found between serum ferritin level and mid-pregnancy fasting plasma glucose and HbA(1c) levels. Although women in the highest quartile of serum ferritin had a greater than two-fold increased risk of GDM, no significant correlation was found between ferritin levels and early postpartum oral glucose tolerance test results. Conclusions: Elevated serum ferritin concentrations in mid-pregnancy are associated with an increased risk of GDM independent of C-reactive protein and body mass index. Ferritin levels in GDM cannot be used as an indicator to predict subsequent glucose concentration in early postpartum oral glucose tolerance test.