Yeah, I thought about that -especially Bowie in his Ziggy Stardust era- but I really don't find that Def Leppard really falling into that trend (and this is where the sound comes in) because Def Leppard really wasn't about the look until the mid 80s (c. Hysteria).
They cite Sweet and David Bowie as big influences on their sound... So even though they didn't take on "the look" until the mid-80s, imho they'd embraced at least elements of the glam sound as early as their inception.
They've recorded their own versions of the Sweet's
Action (on
Retro-Active) and
Hellraiser (on
YEAH!). Also on some of the collector's versions of
YEAH!, Bowie's
Space Oddity was included as a bonus track. They also recorded Mott the Hoople's
Golden Age of Rock and Roll (on
YEAH!) and T-Rex's
20th Century Boy (also on
YEAH!) Since they indicated in the liner notes of
YEAH! that all the songs were those that influenced them and inspired them to be musicians I'd argue that although I wouldn't necessarily consider them to be glam, they are the offspring of that genre.