Dustin originated the role of Samuel "Screech" Powers on Good Morning, Miss Bliss, the 1988 Disney Channel sitcom that became Saved By The Bell.
Speaking to EW, Diamond's team says "It's serious, but we don't know how serious yet".
Per TMZ, the lively performer was in Florida over the weekend and was hospitalized after feeling aches and pains throughout his body.
Sources have told the publication doctors are still running tests to determine what exactly is wrong with him, but his medical team are believed to be concerned it could be a result of cancer.
Although Diamond's Screech was not included in the recent Saved by the Bell revival for Peacock, he was key to the original run of the series, particularly as the comic relief.
Saved by the Bell airs only on Stan.
While most of the Bell cast has gone on to have successful careers like Mario Lopez and Mark-Paul Gosselaar, Diamond has not had an easy time. We would love for him to come back on set.
"I talked to a guy a few times so the book has some truth in it and a lot of the stories were just throwaways".