How Long Does Glyburide-Metformin Take To Lower A1C Level?

My husband has been having the following symptoms. He has lost 20 pounds in 2 months, excessively thirsty, dry mouth, urinating every 30 min., heavy fatigue, occasional confusion, blurry vision. He had a blood test that showed his A1C is 11.1. He has been given glyburide-metformin 5-500 mg. How quickly should that work and how do i know if he needs more immediate medical attention?