Lin et al. [15] studied db/db mice (an animal model of HFpEF and diabetic cardiomyopathy) with adenovirus encoding fibronectin type III domain containing 5 (FNDC5) protein or treated with recombinant human irisin (a cleaved form of FNDC5) with a non-diabetic control group (db/+). Here, FNDC5 is linked to diabetic cardiomyopathy.