Mangaba, what are you saying? A glass of orange juice does produce a spike in blood glucose, in this case in less than 30 minutes, and in my case lasting a bit over two hours.
At least in Florida-grown oranges (and I assume elsewhere), the mix of sugars tends to be close to 50% sucrose, 23-25% glucose, and 25-27% fructose. That does not vary significantly based on maturity of the fruit; but of course the sugars-to-acids ratio does increase over time. It also does not seem to vary significantly among cultivars of C. sinensis.
Certainly, fiber and pectin will have an effect. In the little experiment I did, it was unfiltered, freshly-squeezed juice, so it would have contained the full, natural levels of both, to the extent they were expressed in the juicing process.