I have had a 2+ sugar in urine at about wk33-35 in each of my 3 pregnancies. I refused to do the GTT, arguing that if I could control it properly by diet, then I did not need to be considered to have GD. I did not want to be labled unnecessarily, and end up having my labour options limited as a result.
You need to be very very strict with your diet for the next few weeks, until you give birth and for some weeks after. You must get hold of a list of Glycaemic Indices for foods (I'll have a hunt in a mo') and eat as much as possible from the lowest ranges, limit the mid-ranges, and avoid the high ranges completely. This may stabilise your blood sugars and allow you to complete the pregnancy in a perfectly normal and safe way.
If, however, your blood sugar is not well-controled by diet, you must, for your safety and taht of the baby, comply with the medical advice.
Once I had proven that I could control my blood sugar by diet, I had no more supervision than any other 3rd trimester pregnancy. I went on to deliver 3 healthy, large babies, normally, and with no problems.