Wouldn't touch it with a bargepole. If you're T2 you need to control it with diet with medication as prescribed by your GP. I take a multivitamin in addition to my meds but wouldn't take anything else.
As eating low carb foods sorted out my Hba1c and BG levels in a few months, I'd not be tempted to spend that sort of money on 'something which works like Metformin' - no thanks.
An Ayurvedic herbal supplement which has bitter melon as a main ingredient. Popular in India where the rates of T2 are only marginally behind China. Personally, I think changes in diet would be more beneficial and certainly cheaper.