hi i make my own. half a can of chopped tomatoes curry pwder chilli powder chicken tikka strips onion and peppers simmer for 8 mins. i dont do rice but i have vegtables with it and i dont get a rise or drop in bgs for 3 hrs i think its to do with the amount of fibre
By law they should list the ingredients so do check, most curries do contain sugar but how much depends on which type it is, have a go at making your own as bedshaped suggests.
I buy the supermarket curries WITHOUT the rice, and cook a small portion of my own brown basmati rice (low GI) The curries vary, but the Jalfrezis seem to have the lower carb content. Sainsburys Jalfrezi is only about 7 grams carbs per large portion I seem to recall.