My 13 and half year old son (diagnosed two years ago) is going through very similar experiences. I think he just chooses not deal with it (denial). When he was diagnosed at age 11, his endo told us that as he enters adolescence and puberty that he will more than likely "rebel" against his diabetes because it's not something "cool" or "popular" with others and is a big responsibility that teenagers naturally don't want! (who would want to deal with that at any age?)

However, my own personal opinion goes something like this:
Because they are going through a rather dramatic change, both physically and emotionally, in this phase of their life, the last thing they need is to be different from their friends and have the added responsibility of health issues.
Secondly, because my son has been fortunate enough to have his BG levels very well managed, (A1C of 6.7), he doesn't really think there's a problem. I'm positive that if he were having consistently high BG, he'd understand the need for extreme diligence in managing his Diabetes.
Basically, I think having a disease that takes maturity to handle, combined with the pressures of school, friends, changing bodies and all the other
"pleasantries" of puberty

, they choose to ignore what they see as "not a problem".
Shelly
Son diagnosed with T1 in January of 2010