Diabetic nephropathy (DN) is one of the most common microvascular complications in diabetes mellitus. Ginsenoside Rg1 (Rg1) is an important active ingredient extracted from Panax ginseng. This study aimed to investigate the role and molecular mechanism of Rg1 in DN model.The mesangial cell line HBZY-1 was induced by high glucose (HG; 30 mM D-glucose). HG-induced HBZY-1 cells were treated with Rg1 (2.5, 5, 10 µmol/L). Cell viability was measured by the MTT assay. Apoptosis was detected by flow cytometry. Related proteins were measured by western blot. Reactive oxygen species (ROS) production was measured by dichlorodihydrofluorescein diacetate (DCFH-DA). Inflammatory factors and molecules associated with oxidative stress were detected by enzyme-linked immunoassay (ELISA). DN rats model were treated with 50mg/kg/d Rg1 for 8 weeks, the histopathological changes and the expression of relevant markers were analyzed.We found that Rg1 treatment markedly elevated the survival rates of HG-induced HBZY-1 cells and reduced apoptosis induced by HG. Rg1 treatment attenuated the HG-induced inflammatory response by decreasing the high levels of TNF-α, IL-1β, and IL-6. Furthermore, Rg1 treatment alleviated HG-induced oxidative stress by decreasing ROS generation, malondialdehyde (MDA), and lactate dehydrogenase (LDH) accumulation and increasing the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). After Rg1 (50 mg/kg/d) treatment, the severe glomerular thylakoid hyperplasia, glomerular atrophy, tubule dermal cell exfoliation, basement membrane exposure, interstitial edema and inflammatory cell cytoplasmic infiltration were alleviated in DN rats. DN rat model treated with Rg1 (50 mg/kg/d) showed good anti-inflammatory and antioxidant activities. Rg1 treatment also increased the levels of the phosphorylation of PI3K (p-PI3K) and AKT (p-AKT) and promoted the transfer of FOXO3 from the nucleus to the cytoplasm in vitro and in vivo.Rg1 exhibited protective effects on DN-induced inflammatory responses and oxidative stress via regulating the PI3K/AKT/FOXO3 pathway in in vitro and in vivo. The results suggest that Rg1 may be a potential therapeutic agent for DN treatment.2021 Annals of Translational Medicine. All rights reserved.