Treatment with low‐dose irisin, but not high‐dose irisin, resulted in a statistically significant decrease in collagen deposition as compared with the DM group; moreover, the intramuscular and perivascular fibrosis areas were significantly lower in the low‐dose irisin group than in the DM and high‐dose irisin groups (Fig. 3). Here, FNDC5 is linked to diabetes mellitus.