The 32-year-old recently moved his family back to his native Carlisle, sparking rumours that he may be about to leave Carrow Road.
These were further fuelled by the impending arrival of Dutch international forward Ricky van Wolfswinkel from Sporting Lisbon for £8.5m in the close season.
But Hughton said: "All I've seen is some press speculation. What we have in Grant is someone who has signed a contract in the summer.
"He has two years left of his contract. I think he started more games than he did last season so this is somebody who is right in there playing games.
"Anything that is heard or written about is very much speculation. For me it has not been an issue."
Norwich end their season with a trip to managerless Manchester City on Sunday and Hughton is expecting a tough game despite the departure of Roberto Mancini from Eastlands this week.
"I was surprised that Mancini went," added Hughton. "There seems to be a fair bit of stability at Manchester City and with the plans that they have for the stadium and the area it seems that they (the owners) are there for the long haul which is a good sign in our game.
"The players are quality players. They are guaranteed second place. It's their last home game of the season and they will certainly want to finish on a high.
"The odds are against us because they don't lose many games at home."