Bambi, its truly all in the mix of calories.
Simply put, "carbs bad", particularly for diabetics.
It boils down to two principles: Find the level of calories you need on a day to day basis to maintain your weight, then find the mix of fat/protein/carbs (in that order of contribution) that will satisfy that calorie load while being able to maintain your BG.
The tricky part is weight gain/loss is not strictly a factor of the calorie count -- it depends on the mix too. More carbs == more insulin, which will tend to put weight on for the same total calories overall (fat/protein/carbs), than a lower carb mix.
BTW, I dismissed this law-carb stuff for years and years as just health-nut wackiness like forest elves and crystal healing (I live near Santa Cruz CA, and you wouldn't believe some of the things people truly believe around here). After some extensive research over the last year, after I started using insulin, I'm 110% in the low-carb camp.
Try this: One weekend, eat only meat. Go to the store, buy a bunch of stuff you like -- lunchmeats, steaks, chicken breasts, whatever. Marinate some cut up boneless chicken in teriyaki, and BBQ some skewers. Point is, figure out how to satisfy and satiate your hunger with meat. Like bacon? Bacon and eggs for breakfast!! No carbs.
Toss in no more than 30-50 carb a day on top of that for each of the two days (and bolus accordingly). Then, come back and tell us about your experience: How did you feel? How much insulin did you take? How was your BG control?
I was floored the first time I tried this. These days, I stay under 100g carb most days, trying to get it down to 50 or so.
Insulin directly stimulate fat cells to convert glucose in the blood in to fatty acids, and store it as fat.