I'm also really interested by this, I'm a frequent gym goer and I see lots of guys who do look pretty amazing, like almost impossibly good - but who simultaneously don't seem to have any real strength or stamina. I look like a bag of turds in comparison, despite being very fit and strong, even at my peak as an international swimmer, I didn't look anything like as good as these modern gym guys with all these supplements and potions.
I've also noticed, some of them - not all of them have real bad skin problems and things like acne, along with insane mood swings - some of them scare me a bit and seem very volatile.
It seems there's this craze to look a certain way in no time at all, being fit and strong doesn't seem to matter - it all seems cosmetic, it can't be good for people. The diabetes thing is interesting too - I read something similar in athletes who were consuming gigantic amounts of carbohydrates (energy drinks, gels, power bars etc) before training, which is interesting because you'd think that you'd be burning it all off - but maybe it causes too much of a high load on the endocrine system, as all of those sugars still have to be metabolised.