To dissect the specific mechanism linking IR-dependent signaling to the sinoatrial node (SAN) conduction system without the systemic effect of hyperglycemia, we generated cardiac conduction cell-restricted IR and/or IGF-1R knockout (KO) mice; this was based on the notion that insulin signaling in the heart is transduced through IR and IGF-1R. The gene discussed is IGF1R; the disease is Hyperglycemia.