The Glucose Tolerance Test (GTT) is highly recommended, especially if you have a history of PCOS. It is completely safe and very crucial to detect early gestational diabetes to keep the baby safe.
The only real challenge is keeping the sweet glucose drink down if you have bad morning sickness. Ask the lab to keep the water cold or sit in a cool spot so you don't throw up during the waiting period.
I had to take the GTT early on in my pregnancy because of my IVF history. The sweet syrup might make you feel slightly nauseous, but the test itself is safe and very important for monitoring.