Is there an insurance deductible on glass?

It depends on your coverage. Glass is typically comprehensive and some policies have ded's and some don't. You may want to check with your insurance company as all policies and companies differ.

Additionally, many States expressly prohibit insurers from imposing deductibles on winshield replacement claims. The public policy basis for this is so that owners/drivers will not be dissuaded from having windshields replaced for financial reasons. A damaged windshield can result in visibility/safety issues, and it is in the public interest to avoid these.