The 25-year-old Cutler found out about two weeks ago that he was diabetic and needed daily insulin injections, Garafalo told The Associated Press.
He said Cutler was managing his disease and "in no way is his football career jeopardized."
Some 21 million Americans have diabetes, meaning their bodies cannot properly turn blood sugar into energy. Either they don't produce enough insulin or don't use it correctly. With the Type 1 form, the body's immune system attacks insulin-producing pancreatic cells, so that patients require insulin injections to survive.
"It's something that he's dealing with and something a lot of other people have," Garafalo said. "Even though it's a serious condition, it's a condition that can be managed. That's the way he's treating it right now.
"Everything's fine," Garafalo continued. "His condition is fine."
Cutler, entering his third NFL season, threw for 3,497 yards and 20 touchdowns last season after supplanting Jake Plummer with five weeks left in the 2006 season.
The 6-foot-3, 233-pound Cutler was taken by the Broncos with the 11th overall pick of the 2006 draft, becoming the first Vanderbilt player taken in the first round since 1986.
Cutler is expected to address the media on Friday.
Other athletes who have competed with diabetes include Hockey Hall of Famer Bobby Clarke,
Charlotte Bobcats forward Adam Morrison, golfers Scott Verplank, Michelle McGann and Kelli Kuehne and Olympic swimmer Gary Hall Jr.