You need to know the ingredients really. Do they add sugar, starch thickeners? What vegetables are in there? Are you having rice or other carbs with it? If you call them, they should be able to tell you.
I ASK AT MY LOCAL Bangkok INDIAN which have sugar added and then look at ingredients to spot things like potatoes etc which I avoid Rice of course is a no no On the whole I stick to Chicken Tikka and Kebab type dishes and some similar dishes. or Fish