In our study, mitochondrial dysfunction was apparent in the HG-treated cardiomyocytes and DCM, as demonstrated by the downregulated expression of the mitochondrial dynamic-related protein Mfn2, mitochondrial biogenesis regulation protein PGC‐1α, and mitochondrial gene Cyt-b. The gene discussed is MT-CYB; the disease is familial dilated cardiomyopathy.