The biggest difficulty of managing diabetes during pregnancy is the constant change in insulin requirements. Without getting into a whole lot of explanation, hormones produced during pregnancy essentially block insulin, making it less effective. This is experienced by many women on a smaller scale during their monthly cycle. According to "Think Like a Pancreas" by Gary Scheiner, insulin needs during pregnancy follow this general pattern:

• Week 6: Insulin needs start dropping
• Weeks 9-11: Insulin needs dip to their lowest
• Weeks 12-16: Insulin needs increase to pre-conception levels
• Weeks 16-36: Insulin needs steadily increase
• Weeks 36-birth: Insulin needs taper off and may decrease
• After birth: Insulin needs dramatically decrease, potentially to below pre-conception levels

A note about breastfeeding: it's been stated by many that breastfeeding reduces insulin requirements. I've read stories of women who experienced a drop in blood sugars directly after a breastfeeding session.

With that being said, my own insulin requirements differed as you can see below:

• Week 3-6 (edited): I originally posted that I experienced a huge increase in insulin needs during this period. I wasn't on a CGM at this point in my first pregnancy. Since then, I've learned about how my hormones and cycle affect my blood sugar. Now that I'm going through a second pregnancy, I would say weeks 3 & 4 were the equivalent of my luteal phase with slight resistance. As soon as I hit week 5, I started experiencing some spikes. I had to make sure to prebolus before carbs, and increased the basal setting on my pump.
• Weeks 6-15: Reduction in insulin needs to below pre-conception levels (I felt almost like a "normal" person during this period and wish I had taken advantage by eating more pancakes and milkshakes!)
• Weeks 15-17: Insulin needs increase back up to pre-conception levels
• Weeks 17-36: Insulin needs steadily increased each week (Towards the end of this period, I was taking more than 5x my pre-conception doses and couldn't even look at a carb without spiking.)
• Weeks 36-birth: Slight decrease/stabilization in insulin needs
• After birth: Significant drop in insulin needs to below pre-conception levels.
• Breastfeeding: I didn't notice a huge reduction in insulin requirements during breastfeeding, though I experienced very little insulin resistance and relatively stable blood sugars.
• Weaning: When LO ate significantly more solids and I stopped pumping, I got my period back (around 9.5 months postpartum). I experienced a dramatic swing in hormones that definitely affected my blood sugars. I experienced resistance and an increase in insulin needs. After a couple of months, things seemed to stabilize back to pre-conception levels, with some resistance around ovulation and during the luteal phase of my cycle.

That's it! YMMV, but I hope you found this helpful. It's nice to have a general idea of what to expect during pregnancy. I highly recommend a CGM to help manage the constant fluctuations in blood sugar. Staying active is also a huge help...I did a TON of walking during pregnancy. Good luck!