Pregnancy is susceptible to oxidative stress and antioxidant defenses can be altered in response to elevated levels of oxidative stress. Limited data in gestational diabetes mellitus (GDM) suggest that products of lipid peroxidation may be increased and antioxidant enzyme activities decreased, although the results have been inconsistent. As in type 2 diabetes mellitus (T2DM), glycemic levels in patients with GDM correlate with concentrations of lipid peroxides. The effects of supplementation with antioxidants or antioxidant-rich food in T2DM are controversial. Whether or not increased antioxidant intake can reduce the complications of GDM in both mother and fetus has not been explored.