Diakite was signed on a free transfer from Lazio by Paolo Di Canio last summer, but struggled to hold down a place in the team following the Italian's exit and was subsequently loaned to Fiorentina in January.
The 27-year-old made nine starts in Serie A and agent Ulisse Savini says that discussions regarding Diakite's future will take place over the summer after enjoying his time back in Italy.
"The player is simply on loan from Sunderland, we'll talk with Fiorentina to know if there is the will to keep him," he told Lady Radio.
"From our side there is maximum availability to stay, Modibo is happy in Florence and in the team.
"In January, there were several requests for him but we chose Fiorentina and we are happy with the choice.
"Now we have to also understand if Sunderland will want to focus on Diakite or if they evaluate the player as they did in January, in which case they would ask for money to let him go."