Moreover, our study may also suggest that the reduced risk of diabetes related to lowered resting heart rate ( 4 ) or increased heart rate recovery ( 12 ) cannot be well explained by the lowered irisin levels that coincide with decreased risk of diabetes ( 13 ), albeit irisin is associated with improved metabolic profile and could ameliorate insulin resistance and increase glucose uptake in skeletal muscles ( 14 , 15 ). Here, FNDC5 is linked to diabetes mellitus.