I have T2 but until I was pregnant in 2011, it was managed with diet and metformin. I knew I was going to fail the glucose challenge test, I did. I was put on a sulfonylurea which was an unmitigated disaster when it came to rapidly tanking blood sugar and general feeling like crap. Then I was placed on insulin and it was like a whole new world and with tight control over what I ate along with religious blood sugar monitoring my A1C went below 6.0 for the remainder of the pregnancy. Little Miss was born full term at 7lb, 2oz and no complications.
I stayed on the insulin for 6 weeks post delivery and then went back to metformin which worked well enough for the next two years until it didn’t. Frankly I expected it because my mother had T2 diabetes as well. I’ve been on insulin for 3.5 years now to good effect.
Personally speaking I felt the fog effect after my blood sugars had been trending high for a while and then made it consistently into controlled range. I think your body gets used to being a certain way and then when it is doing what it’s supposed it doesn’t feel so great until it gets used to it again.
All the best!