The energetic Diaby has been plagued with a series of injuries throughout his Gunners career, but the 28-year-old played 45 minutes against Boreham Wood in last weekend's pre-season friendly.
Wenger told the club's official website: "If you get a fit Diaby back, it will be a major asset for our team. At the moment we go step by step and he came through this game so that's very good news for us.
"You wish that he just gets through the game, which happened here - I'm very pleased with that."
Diaby lasted just 16 minutes in his one and only Premier League appearance last season.