The effect of metformin on myocardial sensitivity to ischemia in rats with neonatal streptozotocin T2DM was investigated using the model of global ischemia-reperfusion in the isolated perfused heart. Metformin administration had no effect on infarct size. At the same time, infarct size in T2DM was significantly lower than in controls, which is indicative of the phenomenon of metabolic preconditioning in T2DM. The protocol of metformin administration used in this study had not afforded a significant cardioprotective effect in animals with T2DM.