it's because of hormone changes, and the fact you're growing. once you are in your teens things can sometimes get out of whack, and you need to start adjusting things differently. i had the same problem around that age. i've been diabetic since i was 10 years old. go see your endocrinologist and talk about how things are going, and what you can do to help it. your endo should be able to tell you how to adjust things. if you aren't on the pump talk to your dr. about that because it really helps....especially going thru this time in your life. tell your mom and dad about this too, and they can help you with remembering to take your insulin if you are forgetting, or to not eat so much if you've already eaten a lot....i know these things can be a problem sometimes, it used to happen to me a lot. let me know if you have any more questions....i'd be glad to help.