Are fruit juices a good source of sugar for diabetes patients?

No: Many fruit juices contain high fructose corn syrup which is a simple sugar that will cause a rapid spike of serum blood sugar and is rapidly used by the body. It is better to eat the actual fruit or drink 100% fruit juice with more complex sugars that will sustain the body serum blood sugar longer. So buy a juicer or eat the fruit and help out your diabetes and save some money.

Yes and no: Fruit juices have fructose as the main source of carbohydrate. This contains some glucose but not as much as other sources. You should still watch your blood sugars as you did before.