The users are not fad dieters or methamphetamine addicts, but people with diabetes. And the subject of their rhapsodies is not a gray-market diet pill sold on late-night television but Byetta, a federally approved diabetes medicine, available only by prescription, whose popularity and sales have soared since its introduction last June.

The drug seems so effective for weight loss that some nondiabetics have begun using Byetta as a diet drug — causing concern among doctors who say such use has not been medically tested and could be dangerous.

Ref | New York Times