The best diet for diabetes is the diet that you can stick with in the long run if that diet doesn't have a deleterious effect on your blood sugar levels.
Almost any diet is better than the "standard American diet" of a lot of fast food and other restaurant meals that are high in starch as well as high in fat.
So use your meter to see how your diet is affecting your BG levels as well as your weight loss. Your reading of 419 is much too high and will contribute to the gradual destruction of your beta cells. You should try some medication to get those numbers down. You want to keep your numbers below 140, and then only for a little bit after meals. Under 120 is better.
Exercise is more effective in helping you keep your weight off than it is in losing weight.
If you've never tried a low-carb diet you might consider that. Weight Watchers tends to be high in carbs, although they keep changing their diets and I don't know exactly what they're prescribing today.