Hi
How are you feeling about being diabetic? I was diagnosed type 1 in August and I can't imagine how it must be for teenagers to have it. I am 28, but I work with teenagers all day long so I know a bit about how things are for you

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Obviously you do need to sort out the smoking and snacking, but it takes time to sort things out, so don't feel overwhelmed. Just in the three months since I started on treatment lots of things have improved which seemed impossible at the beginning. It takes a while to learn how to deal with diabetes -I don't feel like I'm there yet but my blood sugar is acceptable.
Have you tried going to the GP to ask for patches? Or is there a friend who can give up with you so you don't feel like you're the only one? Have you tried getting a jar so that you can put in all the money you would have spent on cigarettes? You can use that money to treat yourself after it has built up a bit. Another thing you can try is writing down all the times in the day when you smoke (usually there is a pattern, like before school, break, lunch, way home from school etc) and then try to think of other things to do at that time, like phoning a friend, hanging out with a group who don't smoke, chewing gum etc.
With the snacking, you don't have to stop - I snack all the time, I'm always eating. But I have swapped the snacks for things which don't mess up my blood sugar as much. I eat a lot of fruit/carrot sticks/nuts etc which are much easier to deal with than chocolate and crisps!
Good luch