How does an Insulin Pump work?

My girlfriend has Type 1 Diabetics (And I'm scared because that types bad and she could go blind or die from it??? :\ and her sugar is above 600 a lot for NO REASON, she barely eats sugar, she's 13... will it go away when she hits 20+? Maybe it's puberty thats interfering with her sugar being high?) and I was wondering how does an Insulin Pump work... she's told me once, but I don't understand... is it like hooked up to your body??? she has it on her waist... so does a needle like poke her or something and she feels it getting dumped into her body? (Like Heroin) And is it true that taking too much Insulin is bad for you?