FNDC5 and diabetes mellitus: Irisin, also known as “exercise hormone” released during moderate aerobic endurance activity,19 has shown to exhibit many beneficial effects in treatment of cardiovascular diseases, diabetes, hyperlipidemia and smoking.17,19 Results of current study showed administration of r-irisin attenuated nicotine-induced oxidative stress by up-regulating serum antioxidant enzymes levels, thus establishing the protective role of irisin (Table-I).