Did you try Metformin ER? Many people find the Extended Release version is more tolerable.
I have to tell you, I am not a fan of the sulfonylurea drugs like Glipizide. And while there are arguments about whether sulfonylureas “burn out” beta cells, the evidence is very strong that these drugs are not “durable.” After an initial improvement they “fail” and they fail at a rate that suggests that after a couple of years you might be worse off than if you didn’t take any medication. Below is a chart from the respected researcher Ralph DeFronzo on studies of of the durability of glycemic control of sulfonylureas.
Durability of glycemic control with sulfonylureas. Summary of studies examining the effect of sulfonylurea treatment versus placebo or versus active comparator on HbA1c in T2DM.
Note that these studies compare treatment against a placebo and pay attention to the curves after 3-4 years. You end up worse than if you just took a placebo.
I personally refuse to take a sulfonylurea. I know some people that have done quite well on them. I just think there are other medications out there that work, are “durable” and over the long-term don’t leave you worse off than you would be taking a sugar pill.
ps. And sulfonylureas can cause hypos particularly when fasting or exercising, almost no other type 2 medications have this problem.
pps. And having GD means that you do have a higher risk of type 1, it would be prudent to ask your doctor to order the appropriate tests. @Melitta has written a very good guide to proper testing and diagnosis of T1.