My little sis is diabetic, has been since she was 20 about 4 years ago.
We did some DIY nutrition as she was (she's in v. good shape, very fit, i might add) struggling to understand the randomness of her sugar levels. She took all her shit on time and the right amount but, over time, you become less sensitive to the insulin, and this can be affected by everything from caffeine to her period. Annoying much?
Anyway, we did some research and came up with a ZERO carb plan, it was basically paleo, WITHOUT fruit, but WITH high-fat low/no carb dairy. All in all not a horrible diet.
The next bit is the naughty bit... we binned (not literally) ALL her insulin. She didnt take during the day, she didnt even take her basic slow-acting-over-the-day-whos-name-escapes-me one to set her up. Reason for this was that the SLOW one was fucking up her intense training, her training would razz all the sugar from her blood, but the insulin would KEEP acting putting her dangerously close to a hypo. That's why we stopped that one.
All this is fine and dandy, but we found, over a period of about 7 days, ketones in her blood (the waste product of burning bodyfat) would build up to "dangerous" levels. Ketones are removed from the body by insulin... this was the thorn in the plan's side.
In the end, we had a single carb based meal every 3 days (not day, but one meal only) and she had the instant-insulin immediately before/after that meal. This kept her ketones at a safe level and everyone lived happily ever after.
Now she's married and has a child so doing zero carb is very fucking tricky for her, but she keeps it low-low year round as she found the NHS guidelines of eating predominantly carbs as the basis of your entire diet, as fucking stupid and flawed. Why eat that which fucks up my BS levels!
There you go, DIY internet nutrition for you, take what you want from it, dont blame me for anything that happens....