AFAIK the standard American diet has about 250g of carbs. 132 grams of carbs is about the standard recommendation for T2 diabetes.
That said these recommendations are bullshit. If you have diabetes, you have an insulin problem and it's best to minimize it, so you need to eat the minimum amount of carbs you can get away with, prioritizing the complex carbs with fibers (e.g. spinach and other greens).
Btw, a low calories diet can work even if higher in carbs, because:
1. by losing weight insulin sensitivity goes up afaik
2. at 800 grams per day, that's not much to eat, so those people are probably fasting for much of that day
That's just a guess, but how you distribute your meals also matters just as much as what you eat.