Since I was misdiagnosed as a Type 2 twenty five years ago, I have taken just about every 'Type 2' diabetes Meds available. Imagine the medical community's shock when nothing worked, except insulin - sort of.
I've been on insulin since the initial diagnosis in the hospital. (Well, there was this 2-3 year stent where I stopped needing insulin completely two years after diagnosis, starting the day after my appendectomy - but that is another story.)
Without metformin, I was taking upwards of 140 units/day and still was not 'controlled'.
After a while (and a variety of failed treatment strategies, I decided to take charge and fire the stupid doctors I had and start managing it myself. I did a lot of research and found a doctor that I could work with. After lots of trial and error we finally found something that works for me - a pump and metformin.
Suffering from insulin resistance, the metformin, is very effective (for me) in moderating the glucose dump from my liver after/during meals (and increased glucose uptake in peripheral muscle tissue), eliminating the complications from hyperinsulinemia combined with hyperglycemia.
Never got around to antibodies testing due to the aforementioned stupid doctors and cheap insurance companies. And recently with an A1c of 6.0, an average BG of 114, and essentially zero hypos; there really is no need (and my current insurance company will not authorize them) because it will not effect my treatment.
Without food intake (I had the unfortunate opportunity to test this a few times recently - can't eat for certain medical procedures and could not take the metformin) I don't even need it and can maintain my BG at basically whatever number I want and it remains flat without much variability.
However, if I eat without having metformin, I routinely get BG's in the 250-300, or higher, range. This happens with my routine diet and insulin dose. So yes, it is extremely effective for me.