Abstract: Objective: To investigate the effect and potential mechanisms of soybean isoflavones (SIF) on the efficacy of lowering blood glucose and repairing testes in rats with subacute aging diabetes mellitus. Methods: After 6 consecutive weeks of administration of SIF by gavage on subacute aging diabetic rats, the fasting blood glucose, body weight, oral glucose tolerance and insulin levels were measured in rats. Also, enzyme-linked immunosorbent assay kits were used to detect the levels of superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT) and glutathione peroxidase (GSH-Px), and the morphological changes. Moreover, expression of genes and proteins related to janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling pathway was measured in testes. Results: SIF could significantly reduce fasting blood glucose, oral glucose tolerance test-area under the curve（OGTT-AUC）, insulin secretion, and increase body mass in rats (P<0.01). All doses of SIF (low, medium, and high doses) reduced oxidative stress, with high-doses SIF had the most significant effect (P<0.01). In addition, SIF significantly down-regulated P53, JAK, STAT3, and BAX at both gene and protein levels, and significantly up-regulated Bcl-2 from both gene and protein levels, in which high-doses SIF showed the most significant effect (P<0.01). Conclusion: SIF significantly ameliorated testicular damage in subacute aging diabetic rats by synergistically regulating blood glucose, attenuating oxidative stress, and inhibiting the JAK/STAT3 pathway, providing a new strategy for the development of functional foods for reproductive dysfunction.