The Ghanaian has been likened to his fellow countryman Michael Essien in some quarters and admits a move to the Black Cats is something he would welcome
The Black Cats have been busy so far this summer: they have snapped up central defenders Modibo Diakite and Valentin Roberge from Lazio and Maritimo respectively, as well as midfielder Cabral from Basel and winger David Moberg Karlsson from Gothenburg.
Duncan, who spent last season on loan at Livorno, is the latest to be linked with a move and he is aware Paolo Di Canio is readying a bid for him.
"I am flattered by the interest of Sunderland," he told reporters. "I know the scout of Sunderland has been watching me.
"To be honest, though, nothing has been done and Inter will have a big say if I leave Inter or not."
Duncan has been dubbed by some as the next Michael Essien, but the talented youngster is not getting carried away with the comparisons.
He added: "Fans compare me with Essien and if I can have half of his career I will be very happy.
"He is the best midfielder ever in Ghana. He played box-to-box, could break play up and could dictate play at the same time."