Abstract: AIM:To investigate the effect of glucose control with insulin on myocardial ischemia/reperfusion (MI/R) in streptozotocin (STZ)-induced diabetic mice. METHODS: Type 1 diabetes was induced by i.p. injection of STZ and was treated with insulin for 2 weeks. Mice were divided into four groups: sham group, I/R group, DM+I/R group, and DM+insulin+I/R group. Myocardial ischemia was produced by temporarily exteriorizing the heart via a left thoracic incision and placing a 6-0 silk suture slipknot around the left anterior descending coronary artery. After 30 min of ischemia, the slipknot was released and the myocardium was reperfused for 3 h (for caspase-3 activity and nitrotyrosine contents by ELISA, apoptosis by TUNEL) or 24 h (for infarct size by TTC staining). RESULTS: Compared with those in I/R group, infarct size, myocardial apoptosis, caspase-3 activity and nitrotyrosine contents increased in DM+I/R group (P<0.01). Compared with those in DM+I/R group, myocardial apoptosis (P<0.01), infarct size, caspase-3 activity and nitrotyrosine contents (P<0.05) were reduced in DM+insulin+I/R group. CONCLUSION: Type 1 diabetes aggravates MI/R injury and glucose control with insulin attenuates MI/R injury in STZ-induced diabetic mice.