Malbim: He excuses himself; he does not impinge on Hashem's honor. He thinks that He is G-d of gods. They used to attribute different authorities to different powers, e.g. god of thunder, god of wind and tempest, god of rain, god of strength, god of Chochmah, and there is a G-d over all of them. Nebuchadnetzar believes that Elokei Yisrael is that G-d over all of them. He is also Master of kings and reveals secrets. The dream revealed all this, that He rules over all times and kings, to appoint kings and remove them, and knows all hidden matters.