OB is recommending medication - insulin or metformin?

I had GDM with my last pregnancy so I was anticipating having it again but I was able to control it with my diet last time around. This time, my fasting numbers have been creeping up on me. 😩

My regular OB was on maternity leave for a few weeks and one of the other OBs I saw at the practice said her preferred treatment, if I needed it, would be metformin (non-injection, apparently Asians handle it well? We’re both Asian). Im back to seeing my regular OB and she said her preferred treatment is a nightly long-acting insulin. Google has me torn on what to do. On one hand, I don’t love the idea of doing a nightly injection. But on the other hand, I know metformin crosses the placenta, can cause GI side effects, and hasn’t been used or studied as extensively as insulin for pregnant people. Does anyone here have experience with either?