Hi, Silkissez. Welcome to the site!
I can't help with your question about pioglitazone; maybe others here can post if they have experience. A search of the site turned up only one other post, from back in 2009, so....
Pioglitazone is not a medication I see much about in diabetes news. Did your care provider give you a reason why they chose that medication specifically over the many others available? Metformin often does present some digestive issues when people first start taking it. I'm assuming they also tried the "extended release" version of Metformin for you and that didn't work well, either? Some medications just don't work for some people.
Many of us here on the site, though, are managing our blood glucose levels with exercise and the foods we eat. Some of us still need some medication, but the amount usually is reduced and, so, usually side effects are, too. Can you tell us more about your diagnosis and your latest A1c? Changing what you eat may reduce or eliminate the need for medication.