BackgroundDiabetic retinopathy (DR) is a common cause of visual impairment. Apigenin has been shown to have antiangiogenic effects in various diseases. Our study aimed to investigate the role of apigenin in DR and elucidate the underlying mechanism.MethodsHuman retinal microvascular endothelial cells (HRMECs) were exposed to high glucose (HG) to establish a DR model. HRMECs were treated with apigenin. Then we knocked down or overexpressed miR-140-5p and HDAC3, and added PI3K/AKT inhibitor LY294002. The expression levels of miR-140-5p, HDAC3, and PTEN were measured using qRT-PCR. Western blot analysis was performed to assess the expression of HDAC3, PTEN, and PI3K/AKT pathway-related proteins. Finally, cell proliferation and migration were evaluated using MTT, wound-healing assay, and transwell assay, while angiogenesis was examined using the tube formation assay.ResultsHG treatment resulted in reduced miR-140-5p expression and overexpression of miR-140-5p suppressed proliferation, migration, and angiogenesis of the HG-induced HRMECs. Apigenin treatment significantly restored the decreased level of miR-140-5p caused by HG treatment and inhibited proliferation, migration, and angiogenesis of the HG-induced HRMECs by upregulating miR-140-5p. Moreover, miR-140-5p targeted HDAC3, and overexpression of miR-140-5p reversed the HG-inducted upregulation of HDAC3 expression. HDAC3 was found to bind to the promoter region of PTEN, inhibiting its expression. Knockdown of HDAC3 suppressed the PI3K/AKT pathway by elevating PTEN expression. Furthermore, apigenin inhibited angiogenesis in DR cell models through the regulating of the miR-140-5p/HDAC3-mediated PTEN/PI3K/AKT pathway.ConclusionsApigenin effectively suppressed angiogenesis in HG-induced HRMECs by modulating the miR-140-5p/HDAC3-mediated PTEN/PI3K/AKT pathway. Our study may contribute to the development of novel therapeutic approaches and identification of potential targets for the treatment of DR.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12886-023-03046-5.