Try reducing everything to low gi foods (ie wholemeal/multigrain bread, brown rice/pasta)

Going low gi means your body won't get a massive sugar hit the minute you eat. Also can you potentially cut some carbs out at dinner. My dd is a type 1 diabetic, so very different to gestational diabetes, but we have her dinner carb intake as relatively low compared to every other meal as we found it took a lot longer to burn off and she stayed higher for longer.

Also different foods have different absorption rates, so if you really want to steer clear of insulin try go into more detail with the dietician.

Good luck