Serum Ferritin and Glucose Homeostasis in Women With Recent Gestational Diabetes

Objectives Serum markers of iron storage have been linked to type 2 diabetes; however, 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 type 2 diabetes. However, in the years after pregnancy, it is not known if ferritin relates to their diabetes risk or the pathophysiologic determinants thereof (insulin sensitivity and beta-cell function). Therefore, 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 that enabled assessment of insulin sensitivity and/or resistance (Matsuda index and Homeostasis Model Assessment [HOMA-IR]), beta-cell function (Insulin Secretion-Sensitivity Index-2 and insulinogenic index/HOMA-IR) and glucose tolerance. Results Serum ferritin did not differ between women who had GDM and their peers at either 1 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 and/or 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, Insulin Secretion-Sensitivity Index-2, insulinogenic index/HOMA-IR, fasting glucose, 2-h glucose or glucose intolerance. Conclusions Serum ferritin is not associated with glucose homeostasis in the early years after a GDM pregnancy.