Back on topic:
I am a Type II Diabetic. I'm lucky in that it was caught VERY early (I get blood tests every 6 months for another condition and they caught it) I'm currently on oral meds (metformin), but very close to be reduced or removed from it because my levels are under control by my diet. I am VERY strict about my diet, as luckily it goes well with my temperment. I am very strict on carbs.
They key with eating carbs (including sugars) as a diabetic is both the type of carbs and what you eat with them. I was advised (and never do), to never eat a carbs by themselves without protien. Also, fiber "negates" carbs when over 5 g per serving, so foods high in fiber are great too. So if I need to eat a piece of toast, put peanut butter on it (and I eat fiber-fortified bread). Of course I don't eat candy/chocolate/sweets at all (although I did have a single white chocolate chip for dessert last night, man that was heavenly!).
In my food preps I have accepted the fact that a lot of storage food simply won't be good for me. Things like Mountain House and MRE's, tend to be high in sugars in carbs in order to provide lightweight energy, and protiens are heavy. I try to balance this by putting away items that are protien heavy (chilis, beans, canned chicken, beef stews) to help balance these out. Unfortunetly what I eat in my daily diets (meat, cheese, specialty high-fiber breads & tortiallas, fresh greens) don't store very well. I'll just have to make due.
The good news is that in a SHTF scenario, it won't really kill you to go off diet TOO much for a few weeks. If I get taken off my meds, I will keep a reserve of them and refresh them every once in a while so that if something DOES happen, I can reutilize the meds to reduce the impact of going off-diet. This doesn't mean that you gorge yourself on pizza and chocolate cake during SHTF, but if you have to eat rice (normally a no-no), well then so be it. It might shave a few years off your life in the long run, but it's better than starving now.