I think Fizz has the right idea. In most cases, you can find a healthy substitute you like.
You can also try and re-frame your thoughts if thinking about diabetes complications scares you. Some people tend to bury their head in the sand when scared and eat more! By "re-framing" I mean that you should try and focus on how healthy you will feel and how much energy you will have if you DO eat healthy.
Think of your body as a machine or car. If you put high quality oil into a car, it will take you where you want to go faster, and will break down less. Same applies to good food and your body.
Some people are actually able to eat only 1 cookie (I have never met any of these people

. If this is the case with you, perhaps allow yourself small treats sparingly and in moderation. 2 cookies 2x week may be fine, but a whole box is not! If you have otherwise good control, know how to count carbs and work treats into your meal plan, and have strong will power, the moderation plan may work for you.
If you are like most people, this will not work!

A better plan is what Fizz suggested. Toss all tempting food out of the house (really!) and stock your fridge with healthy snacks and alternatives. You may surprised to find that eventually, an apple, small piece of cheese, veggies sticks, or a handful of nuts are more satisfying than a greasy handful of chips. Portion and cut up healthy snacks that you can have on you at all times.
Withdrawing from junk food is exactly that...you will go through cravings, and it will be hard. If you have ever seen SuperSize Me, the person in the documentary actually felt *addicted* to McDonald's. Whether they add addictive chemicals to their food much like cigarette companies, or we just love the carb rush and fatty taste remains up for debate.
It will get easier in time. If you do treat yourself, just make sure you eat healthy at your next meal and keep the train rolling.
I aim for the 80% healthy 20% "not" plan. The majority of the month I eat really healthy, and then I allow myself a few cheat meals or snacks.
I also have Celiac Disease, so I know 100% what it's like when you crave foods that your absolutely can't have! In my case anything with wheat, barley, oats (and like 50 other grains) is toxic to me.
So maybe it might help to look at unhealthy and high carb/high calorie/fatty foods as "toxic" to a diabetic. Or anyone for that matter!