The 70-year-old tried to reach out to the ‘Careless Whisper’ singer about his drug habits, but his attempt to intervene saw the famous friends fall out in the noughties.
It resulted in George publicly criticising Elton, who had a well documented battle with drugs himself.
In 2004, George said: “Elton John knows very little about George Michael. He knows I don’t like to tour, I smoke too much pot, and my albums still have a habit of going to number one.”
Five years later, he added: “Elton just needs to shut his mouth and get on with his own life.”
The pair eventually settled their differences but veteran broadcaster Gambaccini claims that their fall out had left Sir Elton distressed.
The 67-year-old The Mirror: “Elton was very upset, we exchanged emails.”
He added that he thought George’s drug use wouldn’t develop beyond smoking marijuana, but as Elton had feared, he moved on to harder drugs prior to his death last year.
The Wham! singer was arrested in 2006 for possession of a Class C drug.
The following year he pleaded guilty to drug-impaired driving after blocking the road at traffic lights in Cricklewood, in North West London.
He was arrested again in 2008 for possession of Class A and C drugs after crashing into a branch of Snappy Snaps. He was charged with possession of cannabis and with driving while unfit through drink or drugs.
He was eventually sentenced to eight weeks in prison, of which he served four before being released.
Following George’s death at his Oxfordshire home on Christmas Day last year, Sir Elton was one of the first of his friends to pay tribute.
Sharing a picture of them together on Instagram, Elton wrote: “I have lost a beloved friend, the kindest, most generous soul and a brilliant artist. My heart goes out to his family, friends and all of his fans.”