In conclusion, circDiaph3 plays an important role in promoting the proliferation of pulmonary artery smooth muscle cells in rats with pulmonary hypertension through IGF1R and PI3K/AKT/mTOR signaling pathways, suggesting the potential value of circDiaph3 in the treatment of pulmonary hypertension. The gene discussed is IGF1R; the disease is pulmonary arterial hypertension.