NOX4 and diabetes mellitus: Consequently, it was shown that metformin regulates the remodeling of the small conductance calcium-activated potassium channels (SK2 and SK3) in the atrial tissues of a rat model of type 2 diabetes mellitus through the inhibition of NOX4 expression (constitutive NAPDH oxidase), but also by significantly suppressing the p38–MAPK signaling pathway (Liu et al., 2018).