hey Jackie,
have they offered you any kind of advice and help at your diabetes clinic or have they just left you to get on with it? Eg have you had advice on what foods have carbs in, and as Ed says, how to adjust your insulin to match the carbs? ANd have they explained about the effect of exercise on blood sugar, since you are planning lots of it with the marathons?
would love to try and help, but it would be good to know what you are already doing and what you already know so that we can maybe give some useful advice.