OPCs also have a mitigating effect on many complications of diabetes, such as diabetic nephropathy, the OPCs can relieve symptoms by its metal chelation capacity, and antioxidant capacity and activate some pathways, such as activation of the p38 MAPK and kelch-like ECH associated protein 1/NRF 2 (Keap1/Nrf2) in a mouse model of Cd-induced diabetic nephropathy [139]. The gene discussed is KEAP1; the disease is diabetes mellitus.