Sharma has been admitted to the Deen Dayal Upadhyay Hospital in Delhi, the report said.
AP Singh, Sharma's lawyer, claimed that it was not a suicide attempt but attempt to murder.
"A few days ago, I met him in jail where he complained about torture inside the jail premises," Singh told IANS.
In 2013, Ram Singh, the main accused and the driver of the bus in which the 23-year-old paramedical student was raped, had also committed suicide in Tihar jail by hanging himself.
The victim was gang raped by six persons in a moving bus in south Delhi on 16 December, 2012. The victim and her friend were thrown out of the bus after the crime. The victim died of grave intestinal injuries on 29 December, 2012, at Singapore's Mount Elizabeth Hospital.
Mukesh, Vinay, Pawan and Akshay were awarded death penalty on 10 September, 2013, by a trial court in New Delhi in the gangrape and murder case, which was later confirmed by Delhi High Court on 13 March, 2014. Their appeals are pending before the Supreme Court.
The case was followed by outrage and protests throughout the country, following which a fast-track trial was ordered into the case.
With inputs from agencies