We investigated the effects of ischemic preconditioning (IP) on reperfusion arrhythmias in type 2 diabetic rats as well as the effects of the insulin sensitizer pioglitazone. Thirty-week-old OLETF rats with or without pioglitazone (10 mg/kgBW, orally) were used as a model for type 2 diabetes. LETO rats served as controls. The incidences and durations of reperfusion ventricular tachyarrhythmias (RVT) were evaluated using a working heart method. After 5 minutes of initial perfusion, the rats were divided into the following groups: 1) control rats without IP (CIP(-)), 2) control rats with IP (CIP(+)), 3) diabetic rats without IP (DIP(-)), 4) diabetic rats with IP (DIP(+)), 5) pioglitazone-treated diabetic rats without IP (TDIP(-)), and 6) pioglitazone-treated diabetic rats with IP (TDIP(+)). Three 2-minute cycles of global diastolic ischemia and 5 minutes of reperfusion before long ischemia were performed as IP. The incidence and duration of RVT in CIP(+) were significantly lower than in CIP(-). There was no significant difference in the duration of RVT between DIP(+) and DIP(-). However, the duration of RVT in TDIP(+) was significantly shorter than TDIP(-). These results suggested that the effects of IP on reperfusion arrhythmias are deteriorated in type 2 diabetic rats. The insulin sensitizer pioglitazone can improve the deterioration of IP against reperfusion arrhythmias in type 2 diabetic rats.