The other suspect in the car, Bilal Abdullah, an Iraqi doctor, has been charged with conspiring to set off explosions, which followed a day after two other failed car bombings in London.
Ahmed, an Indian national from Bangalore, suffered burns to 90 per cent of his body and had been in a coma throughout his stay at a specialist burns unit under armed guard.
His brother, Sabeel Ahmed, 26, is facing trial after being charged with withholding information that could prevent an act of terrorism.
He was arrested in Liverpool on the same day as the Glasgow attack.
Mohammed Jamil Asha, a Jordanian doctor, is the other man facing charges over the attacks.
Mohamed Haneef, the 27-year-old cousin of the Ahmed brothers, had been arrested and charged in Australia for allegedly supporting the bombing plot.
He was released after prosecutors admitted to having insufficient evidence against him.
The Glasgow airport attack followed two car bombing attempts in central London when police discovered two vehicles laden with gas canisters and fuel.
Eight people were initially held over the two incidents and three were eventually charged.