Kim Il-sung, the founder and "Eternal President" of North Korea, ordered his doctors to find a way to make him live to the age of 120, according to his former personal physician.
In 1979, Dr Kim So-yeon was promoted to head the research institute that Kim ordered be set up two years previously to help him reach that remarkable milestone, but she defected to the South in 1992. Kim died in July 1994, at the age of 82.
Dr Kim's revelations come in a new book she has written about the more than 30 years she has spent researching longevity, the Chosun Ilbo newspaper reported.
Dr Kim said the North Korean dictator first came up with the idea of extending his life when he reached 65 and ordered that the nation's top medical experts be brought together to achieve that aim.
The beneficial properties of more than 1,750 herbs that are catalogued in textbooks of oriental medicine were analysed, while the most promising plants were grown and used in experiments.
The first remedy the doctors attempted was to make Kim laugh more often.
"We invited a stage actor to perform a comedy and got 5 and 6-year-olds to do adorable things," Dr Kim said.
Any of the performers who was able to make Kim laugh five times a day was rewarded with the title "meritorious actor."
But the medical treatments that were concocted for Kim had a limited effect, because while the dictator was demanding a miracle cure he failed to take care of his health.
From the age of 78, Kim started to demand blood transfusions from healthy young men.
Dr Kim said the "excessive" treatments that were applied led to side effects and may in fact have worsened Kim's health problems. He reportedly died after suffering a massive heart attack.