kealz: I'm so sorry the diabetic nurse made you feel bad!!
My DH is a diabetic, so I've had to learn about quite a few things that send up sugar levels. It's a tough world to navigate! I don't know if this will be helpful for you or not, but here's a list of things you should avoid if you can, which are much less obvious than cakes and goodies:
-bananas, grapes, raisens, white pasta/bread/rice, white potatoes, large amounts of carrots or other root vegetables, apple juice, high sugar cereals or granola bars etc,
It's impossible to list everything, but the reason why those things are on the no-no list will help you to decide other things that should be too. So banana's, grapes and raisens (as well as other fruits) are actually starches in the way their sugar breaks down. It breaks down very quickly which is why it spikes your leves, and why so many people recommened fruit as an afternoon snack to boost your energy naturally rather than eating goodies. Some fruits however are lower in sugar than others. Citrus fruits are generally pretty good like oranges, grapefrutis, clemintines etc. They are still high in sugar, but it's a good sugar when eaten in moderation. Berries are also a good option, although not in season right now. Frozen works too.
White pasta/bread/rice/potatoes/root vegetables/corn/carrots: These are also considered starches because of the way their sugar breaks down. White pasta/bread/rice has an incredibly high starch content but very little nutritious value. If you can, and don't already, try to eat more whole wheat products like brown bread, whole wheat or multigrain pasta, and brown rice. They won't spike your sugars as high, and your getting the added benefit of fiber. As far as root vegetables, again in moderation they're fine, but if you find yourself eating turnip or squash or potatoes every day, you might want to try and switch it up more often for a side of brown rice instead. They also don't count as vegetables.
High sugar cereals/granola bars etc.-this one catches a lot of people totally unaware! Even if you're eating what sounds like a super healthy cereal with lots of fiber and other grains, check what the sugar count is on the nutrition label. A lot of those cereals use honey to flavour them, which is certainly better than raw sugar, but it will still send up your levels. So check what the sugar content is and make sure you choose one that's on the lower end.
I hope you find that helpful... because it really is a tough thing to get the hang of, and no one should be down on you for trying! If you want any more suggestions you can PM if you'd like. All you can do is try your best, and I have no doubts that you are!