GJA5 and type 2 diabetes mellitus: The study explored the mechanisms underlying prolonged P wave duration in rats with T2DM, revealing that the prolonged P wave duration in T2DM rats was not related to left atrial size but was instead caused by abnormalities in atrial myocyte ion currents and the expression of gap junction proteins Cx40 and Cx43, as well as fibrosis of the atrial tissue.