I can tell you that last night, I went out with my parents for their anniversary and misbehaved badly (onion roll and a quarter, bison chili, honey roasted potatoes, steak in Jack Daniels sauce, a chocolate-hazelnut liquer, and half a (non-dairy) creme brulee), and I’m STILL paying for it. That being said, a) it was worth it, and b) I usually eat exceedingly low carb. Besides challah bread on the Sabbath (which is counteracted to some degree by a few glasses of wine), I probably have less than 15 grams of carbs a day, and even on the Sabbath, under 30-40 carbs.
For me, breakfast is eggs with cheese, cottage cheese, or veggie burgers (Morningstar Farms Prime Grillers, as I recall - the ones in the green box - 4g carbs each) with cheese and mustard. Lunch and dinner are both some form of dead animal, and I try to have salad with one of them. Occasionally, I’ll have one of these low carb wraps I have and make a tuna melt or a deli “sandwich.”
I know that when I was dx’ed, the dietician was telling me 15-30g carbs minimum per meal. I chose to ignore that, and, when I told my endo, he didn’t bat an eyelid. The proof of the pudding was in the 5.2 A1c, though the honeymoon helped that immensely.
I credit the low carb diet with the fact that I can keep my sugars under 150 pretty much permanently with less than 10 units of insulin a day, and, even when I choose to correct, I’m under 12-13. Well, except last night 
But still, soooo worth it . . . .