However, when we analyzed the correlation in the control group, the mild fatty liver group and the moderate-to-severe fatty liver group separately, the serum level of irisin did not significantly correlate with that of insulin (r = 0.100, p = 0.100 vs. r = 0.186, p = 0.210 vs. r = −0.145, p = 0.413) and HOMA-IR (r = 0.092, p = 0.130 vs. r = 0.172, p = 0.247 vs. r = −0.079, p = 0.657). The gene discussed is FNDC5; the disease is fatty liver disease.