During a campaign event last week in Philadelphia, Biden, also a Democrat 2020 presidential candidate, reportedly asked if the US had become "a nation that embraces dictators and tyrants like (Russian President Vladimir) Putin and Kim Jong-un", reports Efe news.
North Korean state news agency KCNA lashed out, accusing Biden of slandering Kim and of becoming "reckless and senseless, seized by ambition for power".
In addition to calling him a "fool of low IQ," the KCNA said Biden was an "imbecile bereft of elementary quality as a human being, let alone a politician", bringing up questionable episodes of his career.
The article referred to the recent criticisms Biden received for his inappropriate behaviour alleged by several women, accusations of plagiarism during his campaign for the Democratic primaries before the 1988 presidential election, and images that show him falling asleep in 2011 during a speech by then-president Barack Obama.
The commentary added that Biden "self-praising himself as being the most popular presidential candidate is enough to make a cat laugh".
The article concluded that Pyongyang will "never pardon anyone who dare provoke the supreme leadership but will certainly make them pay for it".
From the beginning of his campaign for the 2020 primaries, Biden has criticszed President Donald Trump for "stiff-arming our friends and embracing our enemies", called Putin a "dictator" and a "kleptomaniac" and Kim a "thug" who writes "love letters" to Trump.
He also spoke about Kim as "a guy with his uncle's brains blown out, sitting across a table" referring to the 2013 execution of Jang Song-thaek, Kim's uncle and an important figure in the Pyongyang regime.
( With inputs from IANS )