I have PCOS and my bubs was big around the tummy at my 28week scan (93rd centile), so I did the two hiur test which was fasting from 10pm, blood taken at 9.15am (4.01) then the manky drink and still no food until blood tskrn two hours after the drink (4.02). I was normal, so bubs is just chubby, but if you're going for the GTT take some sarnies or something (by the time I could eat and drink again I was famished). GD is usually controllable by diet (I looked into it before the test) and worst case they'll put you on injections, they also induce here at 38 weeks due to the risk of placenta going dodgy and babies who have GD mums tend to be a bit bigger. Best of luck with the test, just know having PCOS doesn't necessarily mean you'll fail the test.