There is no such thing as Dragon Sage Mode.

[Your Creepy Stalker]

It's Snake Sage mode, And the manga says so.
Kabuto saying I'm a dragon now was not because he had dragon sage mode.

 

[Skylar Knight]

I thought this was obvious :|

 

[Kurama04]

I thought this was obvious :|

^_^

 

[Words of wisdom]

I think snakes were seen as dragons long ago in japan.

 

[Dred Locz]

Maybe

 

[gazz uzumaki]

I think it has something to do with the japanese believing that snakes are related to dragons. (don't ask me how)

 

[shadedcrow]

So I wont repeat the other 5 post but say Kabuto had thought of himself as a evolved being after his self experimentation + snake sage mode (chakra at least). Ok so I lied kinda figured it was obvious...