Diabolik is a servant of Slaanesh or some other dark god.He seems dedicated to hedonism, pleasure and decadence. He causes death and destruction "in the name of sex." He is Immuneto Bullets. He comes up with a ultra-cool, high-tech base and gadgets out of nowhere. He is able to put emeralds into a gun and fire them without gunpowder into another man and not miss or have any emerald bullet pass through him. He survives a tide of molten gold. He knows how to fake his death and then come out of it exactly when he wants. He knows exactly when a shipment is a decoy and can go after the real thing; knowledge that he could not possibly have. As Crow on Mystery Science Theater 3000 says "This guy operates under incredible luck and circumstance." I would say that Diabolik is watched over by something supernatural. No wonder the inspector and the authorities are constantly frustrated in their efforts to catch him. Clearly this man is not human or has strange powers.
The Prime Minister is Mad Jim Jaspers before he discovered his powers.The Prime Minister is played by British actor Terry Thomas who the artist based the Reality Warper Mad Jim Jaspers' appearance on. Sir James Jaspers was also Prime Minister. That would make Diabolik's world Earth-238. It would take very little to imagine that there are other costumed heroes of this world, but it was Diabolik giving the Prime Minister the laughing gas that resulted him in hating costumed heroes and villains. It was Jim Jaspers subtle reality warping that resulted in the more impossible things occurring in the film, from Diabolik firing emeralds out of a gun to his leg temporarily disappearing in midair. It's only a matter of time before the Fury and the Jasper's warp dooms Diabolik's world and its universe.