GD Question ( pregnancy)

I did the glucose tests and passed back 2 months ago or so, well last week at my appointment my urine sample had glucose in it so they did a blood draw and it came back my blood sugar was over 200. Now being sent to a specialist. Did anyone else develop GD late in pregnancy? After an original pass? If so did it change anything for rest for pregnancy other then diet adjustments. My baby also was estimated at 7lbs 13 oz at my last US 34 weeks 5 days. My OB is recommended c section if he gets over 9lbs (I have learned that US can vary some). What have others experiences with this been like?