Advice wanted? Pre-diabetic stared in Metformin cannot tolerate the medication

I was recently diagnosed with pre-diabetes. My A1c was 6.2 and I have a strong family history of DM. So I spoke to an endocrinologist who offered to start me on Metformin as I try get my eating and health under better control. I have been exercising and trying to eat healthier. But I often miss 1 of the doses of Metformin. What also makes it worse is that I still seem to have the gastrointestinal issues of the medication after taking it for a month and more. Anyone have this issue as well? Anyone have expertise with the long acting versions of Metformin so I don't have to do twice a day? Should I try different medication? Any advice would be helpful. Thanks