Serum Ferritin and Glucose Homeostasis in Women with recent Gestational Diabetes

Abstract Background Serum markers of iron storage have been linked to type 2 diabetes (T2DM), although the mechanism underlying this association is unclear. In pregnancy, increased serum ferritin has been reported in women with gestational diabetes (GDM), a patient population at high risk of future T2DM. However, in the years after pregnancy, it is not known if ferritin relates to their diabetic risk or the pathophysiologic determinants thereof (insulin sensitivity, beta-cell function). Thus, we sought to characterize the relationship between ferritin and glucose homeostasis in the early postpartum years in women with and without recent GDM. Methods At both 1- and 3-years postpartum, 340 women (105 with recent GDM) underwent serum ferritin measurement and an oral glucose tolerance test (OGTT) that enabled assessment of insulin sensitivity/resistance (Matsuda index, Homeostasis Model Assessment (HOMA-IR)), beta-cell function (Insulin Secretion-Sensitivity Index-2 (ISSI-2), insulinogenic index/HOMA-IR (IGI/HOMA-IR)), and glucose tolerance. Results Serum ferritin did not differ between women who had GDM and their peers at either 1-year or 3-years postpartum. Baseline-adjusted change in ferritin between 1- and 3-years correlated with the concomitant change in C-reactive protein (r=0.21, p=0.0002) but was not associated with measures of insulin sensitivity/resistance, beta-cell function or glycemia. On adjusted analyses, neither baseline ferritin nor its change from 1-to-3-years was independently associated with any of the following metabolic outcomes at 3-years postpartum: Matsuda index, HOMA-IR, ISSI-2, IGI/HOMA-IR, fasting glucose, 2-hour glucose or glucose intolerance. Conclusion Serum ferritin is not associated with glucose homeostasis in the early years following a GDM pregnancy.