After missing out on Euro 2012 with England the forward was named in Stuart Pearce's Team GB squad for the London Olympics, and Di Matteo says there is still a chance he could feature.
"Daniel [Sturridge] has viral meningitis. I spoke to him and he feels better now. Hopefully he gets well ASAP," Di Matteo told a press conference.
"He felt unwell over the weekend and was taken to hospital afterwards.
"We have to monitor Sturridge on a daily basis but the fact he is feeling better is very positive. I am optimistic.
"We can't put a time frame on it but I hope he will return [in time for Olympics]
The news represents a huge blow for manager Pearce, who has already been denied the services of regular Premier League performers Gareth Bale and Kyle Walker as a result of back and toe injuries respectively.
The 22-year old’s potential exclusion leaves Wales international Craig Bellamy and Bolton forward Marvin Sordell as the only recognised strikers in the 18-man squad and Pearce may be forced to raid his standby list for replacements.
Wilfried Zaha of Crystal Palace and Scotland international Jordan Rhodes are thought to be on the list after both missing out on the initial squad despite enjoying productive seasons at club level.
David Beckham’s omission has been the major talking point since the squad was announced on Thursday but Sturridge's withdrawal will not free up one of three over-age slots, meaning the LA Galaxy midfielder is still unlikely to feature.