Huh? 
“Insulated,” okay – if the infection never enters the country, it’s not a problem. (Of course, once it does, the country’s isolationism is moot.) But what does the homogeneity of the population have to do with anything?
North Korea started out as evil, moved on to insane, and has now graduated to laughably stupid. It’s like an Asian The Producers.
Homogenous was just a reference to the fact that they have very little immigration (who in their right mind would want to move there on purpose?) and very little international travel, and therefore less chance than usual for HIV to get introduced in the first place. (Maybe, who knows?)
And then if someone did have the misfortune of being HIV+ in North Korea, I’m thinking they’d never have any chance of knowing, anyway. When would they ever get tested? They’ve probably never run ANY tests, thus their “100% sure we have no confirmed HIV+ citizens” claim could be technically true.
One day the NK’s are going to (completely by accident) make some insane scientific breakthrough (viable cold fusion, room-temperature superconductor, antimatter production with a 9 volt battery etc) and the rest of the world will go: :dubious: 
:eek: :o
And yet, the death rate from nighttime fan use continues to rise.