hi, there's probably enough posts on here already to tell you that your problem is quite common, so I won't bang on.
I had similar problems with ordinary metformin. I took them but would poo them out, seemingly unscathed, a couple of hours later. No chance to absorb them. I didn't experience any other effects.
I then went onto insulin (best control I've ever had) but the documented side-effects of insulin made some well-meaning (know-all!) nurse ask me to reintroduce metformin. I agreed, got the SR because I'd been previously intolerant, and happily experienced no side-effects. By this time I was measuring myself quite closely though and the Metformin SR made no difference to my sugar. So I stopped after about 6 weeks. I was then accused by this nurse of not giving the tablets the chance to reduce my hba1c, but since I test myself regularly with a glucometer, was happy that the drug was ineffective.
I'm cynical but I think that the reason that this happens is just economics. Metformin is the cheapest drug to prescribe for diabetes, so they try that first. SR is a bit more expensive, but not much more.
Do you keep a diary? It might be worth checking exactly how much difference these horse-pills make to your sugar. It may well be minimal in any case.