I also take 500mg metformin after a meal(breakfast and dinner) and was advised to take 5mg glipizide before meals (breakfast and lunch) but sometimes I measure my bs before and notice it's sometimes 70-90 . A little about me: I don't eat at regular intervals, I don't snack , I have 3 meals a day . Wake up at 530 go to work, eat breakfast at 9 and then my lunch around 12 , dinner between 5-630. No snacks. Thank you for taking the time to read this. I don't know much about glipizide just the fact that I have to take it before a meal. Also, how important is it that you have to eat 30 minutes after taking glipizide? Let's say I go over the 30 minutes?