The reaction of King Nebuchadnezzar to the interpretation of his dream marks a powerful climax where the ruler of a massive empire fully acknowledges the absolute supremacy of God. After Daniel refuses to accept worship and offerings, the king speaks up to clarify his intentions. He wants to ensure that he is not offending God's honor or denying His existence [מצודת דוד, מלבי״ם, אלשיך]. He speaks with complete sincerity, declaring what he now knows to be the absolute truth [רש״י, אבן עזרא, ביאור שטיינזלץ].
The king proclaims that the God of Israel is the ultimate God over all other gods. During a time when people believed in many different divine forces controlling specific elements like thunder, rain, bravery, and wisdom, the king recognizes that God is the supreme power who rules over everything [מלבי״ם]. From another angle, the king clarifies to Daniel that even if he views Daniel himself as a sort of divine being because of his immense wisdom, he understands that God is Daniel's God. Therefore, God is far greater and truly the God over all gods [מצודת דוד, אלשיך].
Furthermore, God is recognized as the ultimate master and ruler over all earthly kings [רש״י, מצודת דוד, ביאור שטיינזלץ]. Unlike the deities of other nations, which were thought to be local powers with influence limited to specific groups of people, the rule of God is universal and absolute [אלשיך]. The clear proof of this lies in the dream itself. The vision demonstrates that God controls time and history, raising up and tearing down empires exactly as He pleases, making all mortal kings seem as nothing in comparison to Him [מלבי״ם, אלשיך].
Finally, the king acknowledges God as the revealer of deep secrets, a truth proven in practice when Daniel successfully uncovered the hidden details of the dream [רש״י, ביאור שטיינזלץ]. Daniel's ability to expose such a mystery, especially at a young age, is possible only because the God of heaven is the true revealer of secrets who granted him this special power [מצודת דוד, יוסף אבן יחיא, אלשיך]. Beyond this single event, the uncovering of such a massive historical secret that spans all future generations serves as ultimate proof that God knows every hidden thing and holds all the secrets of the world [אלשיך].