Background:Exercise is an effective approach for controlling DM. the exact mechanism by which exercise can control DM is still unclear. In 2012, Boström and colleagues discovered that in muscle, exercise increases the expression of FNDC5 (Fibronectin type III domain-containing protein5),amembrane protein encoded by the FNDC5 gene. The FNDC5 protein is cleaved and secreted as a new hormone called irisin suggesting that some of beneficial effects of exercise could be mediated by this hormone. The aim of the study was to estimate effect of exercise on serum irisinand fasting blood glucose levels in normal and diabetic rats.
Material and methods:120 adult male albino rats were categorized them into 4 groups.  Diabetes mellitus was induced by intraperitoneal injection of freshly prepared alloxan monohydrate (160mg/kg) in a single dose in Group III and Group IV Physiological saline (0.9% Nacl) was injected intraperitoneally in Group Iand Group II.  
Fasting blood glucose was measured weekly and two months after swimming exercise serum levels of irisin and  insulin were measured.
Results:Exercise increased serum levels of irisin and insulin in both control and diabetic groups alsomeasurement of blood glucose level showed that exercise had decreasing effect on blood glucose in diabetic rats.
Conclusion:Swimming exercise increases serum irisinlevel also improves fasting blood glucose and insulin sensitivityin diabetic rats.