Sera from different groups of rats were used for experiments in vivo and in vitro.<h4>Results</h4>DJB effectively improved oxidative stress and activated the adenosine monophosphate (AMP)-activated protein kinase (AMPK) pathway to increase endothelial nitric oxide synthase (eNOS) phosphorylation level and the expression of antioxidative system-related proteins and genes in the heart of diabetic cardiomyopathy rats. The gene discussed is NOS3; the disease is diabetic cardiomyopathy.