Considering these findings, we hypothesized that the cardiac BCAA levels and the activity of branched‐chain α‐keto acid dehydrogenase (BCKDH), a rate‐limiting enzyme complex in BCAA catabolism that is localized in the mitochondrial matrix, are altered by T2DM, and that upregulated AMPD3 expression is involved in the alteration. The gene discussed is PPM1K; the disease is type 2 diabetes mellitus.