Autophagy dysfunction and apoptosis exacerbate the risk of heart failure in patients with diabetic cardiomyopathy (DCM). However, the interactions between autophagy and apoptosis in DCM and their underlying mechanisms remain poorly understood. This study induced type 1 DCM in C57BL/6 mice via streptozotocin injection and exposed H9C2 cells to high glucose to investigate these mechanisms. The study revealed a significant elevation in autophagic vesicles and compromised autophagic flux, accompanied by pronounced myocardial cell apoptosis in the myocardium of diabetic mice. Long-term exposure to high glucose in H9C2 cells led to enhanced autophagosome formation and impaired autophagic flux, while inhibition of autophagy with 3-MA reduced cell apoptosis. Additionally, we observed an increase in Txnip expression in the myocardium of diabetic mice and in high glucose-treated H9C2 cells, which regulates autophagic apoptosis in high glucose-treated H9C2 cells. Furthermore, Txnip regulates autophagic apoptosis through the modulation of forkhead box-1 (FoxO1) expression and acetylation. Prolonged high glucose exposure resulted in increased levels of phosphorylated sirtuin 1 (SIRT1) and reduced SIRT1/FoxO1 interaction, changes that were ameliorated by Txnip knockdown. Txnip overexpression elevated FoxO1 levels, which could be suppressed by NAC and GSH. These findings revealed that Txnip mediates autophagic apoptosis in DCM by upregulating FoxO1 via ROS and enhancing FoxO1 acetylation through the suppression of SIRT1 activity. The discovery of this new mechanism provides new perspectives and potential therapeutic targets for understanding and treating DCM.