A march in honour of Aboriginal man David Dungay, who died in prison, will take place in Sydney, with his mother to give a speech.

An Aboriginal mother whose son died in prison will address Indigenous rights at a rally in Sydney.

Leetona Dungay's diabetic son David, 26, died at Long Bay Prison Hospital just three weeks before his release on parole in January 2015.

Ms Dungay will address crowds following a march from Central Station to the Department of Corrective Services in Lee Street on Thursday at 11am.

"The Aboriginal people of Australia need to take a stand ... because there's too many mothers like me who have lost their sons," Ms Dungay will say in her speech.

Ms Dungay has previously spoken of her son, who she says died in the prison hospital after he was stopped from eating a biscuit for his blood sugar levels.

The coroner will investigate Mr Dungay's death.