I have a few suggestions that may help you eat less fast food and when you do eat it how you can make sure you are taking the correct amount of insulin. Personally I only eat fast food once a month, that way I get my fix but I'm not doing to much bad by only having greasy food once every four weeks. When I speak of fast food I mean any meal that you eat a restaurant that we know isn't good for us. These foods include, pizza, hamburgers, grinders from places like Quiznos, french fries, and appetizers like potato skins or mozzarella sticks. This makes it tough to go out with friends to fast food restaurants but trust me when I say you can find something healthy on any menu if you really want to. For example try ordering a cup of soup when your out with friends and don't want to use your once a month bad food card. Find the healthiest soup and enjoy, healthy soups fill you up and keep your belly full for hours.
It takes a lot of will power but if you want to avoid bad foods you can. When you do eat those fast food meals however make sure you always test before eating and be sure to use your past experiences to help you figure out how much insulin you will need. I will often get the same meal when I have my monthly fast food meal, that way I know how my body reacts to the food and how much insulin to take. Like anything it takes a little bit of work but in the end the work pays off.