The Spanish goalkeeper, who arrived at Manchester United from Atletico Madrid in 2011, had an outstanding 2012/13 season for Sir Alex Ferguson's men.
And the 22-year-old, who is currently on international duty for Spain in the U21 European Championship in Israel, insists his main objective is to reach the top.
"I have grown a lot," De Gea told Spanish newspaper AS.
"I am more experienced, I have played a lot of games for United, and I am sure of myself and confident.
"Of course, I am very grateful for the effort they (United) made to buy me and for the support they gave me. First Atletico, then United trusted in me.
"My objective is to be right up there with the best players in the world, that's what makes me excited, and I'm doing everything I can to achieve that.
"I am playing at a very high level. I have had one year playing well but I'm still very young. I think that I still have a way to go before I reach the level of the best in the world."
De Gea won a place in the PFA Team of the Year and finished third in voting for the club's Sir Matt Busby Player of the Year award.