If OGTT results after 75 grams of glucose is
Fasting 92 or more
1 hr 180 or more
2 hr 153 or more , This is gestation
diabetes Mellitus.
Only 1 abnormal reading is required to diagnose Gestational Diabetes Mellitus ( GDM)
So your 2 hr has come 166 so it’s abnormal and you have GDM.
Next Steps
You need Medical nutrition therapy ( MNT)
You should keep fasting below 95
1 after PP below 140
And 2 hr PP below 120
Health Tips
For MNT kindly consult