If he's a type-1 diabetic, depending on his age, he might just be fucking fed up with having to deal with it 24/7.....my son is type-1.............if he's type-2, then he probably needs to get in the gym and get healthier....you feel better and your mood improves..........I doubt the statins are the cause of depression......I quit them because of other side effects.....jitters, feel like shit in morning, etc.

By the way, my type-1 son is a stellar athlete with no issues......