Could anyone suggest a good cereal for a diabetics. Is there any cereals without added sugar?

There are many. If you are a diabetic, you would want a cereal with high fiber content. Some of the good ones (not all-inclusive) are: fiber one, kellogg's raisin bran or all-bran original, or my personal favorite kashi golean crunch.
Check labels. Reading labels is a must for diabetics. Start looking at the carb content. There are lots of options out there. For example, plain cheerios has less carbs than raisin bran.