Here in Saudi we use to get 'Udad Flour'. Generally I use it for making 'thenkuzhual'.
Some times for normal dosa. Yesterday I used it in a different way and got good dosa. Here is the recipe. You also try this.

Ingredients:

1 cup Udad flour (dry)
2 cup wheat flour
2 cup rice flour
salt
1/2 sp cooking soda

Method:

Mix all the flours in a bowl and put them in a mixer grinder with water.
Just for 2 to 3 min. so that the fine flour will mix evenly.
Add cooking soda and salt.
Again run the mixie for a min.
Remove and make dosa immediately.
Or even you can keep the dough for the next day.
Me and my hushand liked the dosa very much.
Sugar patients can also give a try to this.
I noticed that this dosa is consuming less oil.

Note: In this dough if you want you can add bombay rava. You can add chopped onions and green chilly with it.