Consistent with the in vitro results, Rac1–Nox2–ROS axis was activated in the retinal microvessels from mice in Diab group, and Rac1–Nox2 activation and elevation in ROS levels were further increased in HF-SD group (p < 0.05 vs Diab; Fig. 6a–c). Here, RAC1 is linked to hydrops fetalis.