Januvia...Not Metformin?

I posted a couple of days ago on my more general story, but I've noticed the meds I've been prescribed are a little odd.
I love my endo, she's been great. But I'm a little concerned. She said I have severe insulin resistance and hyperinsulinemia. The first medication she put me on was actos, half a pill. I had too many side-effects and was still becoming hypoglycemic, so she took me off of it. Then two weeks ago she put me on Januvia. I've had highs and my lowest lows still. I personally don't think it's doing much.
Coming here I've learned metformin is the commonly prescribed medication, it's also much cheaper! Should I be looking at a different solution?

(Side note: I haven't seen my doctor since she gave me the actos. I call her office and speak with a nursing aid who takes down my numbers. Maybe in-person would help?)