Those patients developed acute pancreatitis, which is inflammation of the pancreas. Twenty-one of the patients were hospitalized. None died.
Doctors should discontinue Byetta in patients suspected to have acute pancreatitis and not restart the patients on Byetta unless they find another cause for the patients' acute pancreatitis, according to the FDA.
It's not clear if Byetta caused the 30 reported cases of acute pancreatitis.
Twenty-two of the patients improved after discontinuing Byetta. Symptoms of acute pancreatitis returned when three of the patients started using Byetta again, according to the FDA.
The FDA says that Byetta's maker, Amylin Pharmaceuticals, has agreed to include information on acute pancreatitis in the "precautions" section of the drug's label.
A spokeswoman for Amylin Pharmaceuticals, which makes Byetta, was not immediately available for comment.