Diamond's ambitions of competing at a seventh Olympics in Tokyo next year ended when heart problems recently left him in a Newcastle hospital and he is now on the waiting list for a transplant.

In the meantime, the 47-year-old will undergo gall bladder surgery on Tuesday and two days later auction his 1996 Atlanta Olympic gold medal to help support his family.

Diamond has three children with ex-wife Cathy and also sold his Sydney Olympic gold two years ago for $72,000.

While upset to part with his remaining gold medal, Diamond says he has bigger concerns at the moment.

"I'm feeling quietly nervous about the surgery tomorrow," he told AAP.

"But I've had constant stomach aches with (this) 8 millimetre gall bladder ... so I'm looking forward to getting it out.

"I haven't heard anything (about the heart transplant waiting list). It's just one step at a time," he said.

"The doctor said there's a one in five chance that things could go twistedly wrong tomorrow. Hopefully I just wake up (after the surgery)."

Diamond became the first Australian trap shooter to win gold at the Olympics in 66 years in Atlanta in 1996.

In Sydney, he became just the second trap shooter to win back-to-back golds.

Australian Associated Press