Recent studies have demonstrated a pivotal role for histone crotonylation in gene regulation,[27] with lysine catabolism shown to reprogram tumor immunity through this modification.[28] The diabetes biomarker 2‐AAA undergoes stepwise metabolic conversion and is catalyzed into crotonyl‐CoA by glutaryl‐CoA dehydrogenase (GCDH).[29] Whether the intermediates of amino acid metabolism regulate glucose homeostasis through histone acyl modifications is deserved to be investigated. The gene discussed is GCDH; the disease is diabetes mellitus.