I thought jujube was a candy??

In tamil, jujube is known as Elanthai pazham.

The word Indian Jujube in Hindi is "Ber" (बेर).

By jujube I presume the herb Zizyphus jujube is being referred to. As oppose to the candy which is totally unrelated to the botanical. Andrew Chevallier master herbalist and writer of several major herb books writes jujube is good for stamina, the liver and is a sedative. There is no mention of being a treatment for diabetes. Therefore jujube isn't a good herbal for diabetes.

The scientific name of the Jujube plant is Ziziphus jujuba. It belongs to the family Rhamnaceae and is commonly known as Chinese date.