We bang on about cutting carbs when on pred and I thought you might be interested in this article about extremely low carb diets and reversing diabetes and weight gain. It isn't in pred patients but it does show how going low carb works and that it is sustainable on a relatively low income.
The only catch in fact is that you have to adjust to it being a way of life - you can't cheat and you can't go back to your old eating habits without risking losing the benefits.