My insulin needs shot up at around 25 weeks. I started to get lots of highs eg my blood sugar after breakfast was suddenly 12 when it would normally be 5. I'm on a pump so I increased my basal rates slightly, but the major change I made was upping my boluses.
My insulin to carb ratio is now 1:5, up from 1:10. A big change!
My consultant says not to limit my carbs but to have as much insulin as I need to keep my sugars within range.
NB - I have Type 1 diabetes. If you don't, your needs may be different.
An increasing need for insulin is a good thing, my consultant said, as it shows the placenta is making all the hormones it should : )