your healthcare provider may gradually increase your glipizide dosing if necessary to a maximum of 40 mg per day the dosage of glipizide glucotrol or glipizide extended release glucotrol xl your healthcare provider prescribes will vary depending on a number of factors includinghe dosage of glipizide glucotrol or glipizide extended release glucotrol xl your healthcare provider prescribes will vary depending on a number of factors including