An alternative therapy practitioner who claimed slapping and stretching could cure diabetes has been found guilty of manslaughter after a six-year-old boy died following a "slapping healing" workshop four years ago.

The boy, who cannot be named, had type 1 diabetes and was given his final insulin injection on April 22, 2015, at the beginning of a week-long workshop at Hurstville in Sydney's south.

Hong Chi Xiao has been found guilty of manslaughter. Credit:Facebook

He died five days later, after he began to vomit a black-coloured substance and became so weak he was pushed around in a pram. On the day of his death, when he could not talk or open his eyes, participants at the workshop slapped his arms to wake him up.

The boy was also slapped on the arms that evening, after he had a seizure and laid on a hotel bed unconscious and not breathing. He died from diabetic ketoacidosis, a build-up of acid in the body after no insulin is administered.