The 84-year-old Mubarak who is being held at a military hospital in Cairo, has been treated for a heart condition, fractured ribs, fluid in the lungs, depression and high blood pressure, according to lawyers and official accounts.
At one point last year he was even declared clinically dead as he slipped into a coma.
There were questions over whether he would appear in court on Saturday for his scheduled retrial along with his top security chiefs for their alleged complicity in the murder and attempted murder of hundreds of peaceful protesters in January 2011.
But on Saturday, Mubarak was in the dock, sitting upright and looking strong. Wearing sunglasses, he waved and smiled at supporters, chatting casually with his two sons Alaa and Gamal who face corruption charges.
In the event, the retrial came to an abrupt end with the main judge stepping aside and sending the case to the court of appeal, which will then refer it to a new circuit.
"I expected to see a sick old man and I expected to feel sorry for him," said Cairo resident Heba Radwan. "But the pictures of him smiling and waving, they were so provocative."
His demeanour was in stark contrast to the pictures of a pale and ailing Mubarak at the start of his trial in August 2011.
"Mubarak in top form" read the headline of the state-owned Al-Akhbar.
"I was furious when I saw him in the cage," said Ahmed al-Sayyed, who works at a Cairo cafe.
"I had forgotten about him. I didn't even watch the trial live. But when I saw him on television later, I couldn't believe the provocation," he said.
Procedural failings
In January, Egypt's highest court, the court of cassation, ordered a retrial for Mubarak after accepting an appeal against his life sentence, citing procedural failings.
Former interior minister Habib al-Adly had also been sentenced to life for his involvement in the deaths of the protesters, but controversially his security chiefs were acquitted, sparking widespread anger and protests after the verdict in June.
President Mohamed Morsi, who won elections last June on the Muslim Brotherhood's ticket, had pledged new trials for former regime officials, including Mubarak, implicated in the protesters' deaths.
But Morsi's presidency has been plagued by unrest and deadly clashes between protesters and police, a revolt in the canal cities, sectarian violence and a devastating economic crisis, in what many fear is taking Egypt to the brink.
Mubarak had long warned that if he were to step down, chaos would sweep the country. Some say that a feeling of vindication may explain his attitude in court.
"Thanks, Guys", read the headline in the independent pro-revolution daily Al-Tahrir which also translates as "Thanks Brotherhood", a reference to Morsi's Muslim Brotherhood which has dominated politics since the uprising.
"The revolution struggles, Mubarak smiles," said the independent daily Al-Shoruk.
A cartoon in Al-Tahrir shows the trial judge asking Mubarak where his lawyer is.
"Why do I need a lawyer or defence? Morsi, bless him, has done a great job," Mubarak replies. – Sapa-AFP