The study compared data from three long term studies and looked not only at fruit vs juice intake, but also the types of fruits eaten. The study found "Replacing three servings per week of fruit juice with individual whole fruits reduced the risk of type 2 diabetes by 7%. In contrast, greater consumption of fruit juice was associated with increased type 2 diabetes risk."
Keep in mind that the study does have it's weaknesses such as relying on people's personal recall of how much fruit they consume. Most of us can't remember what we ate yesterday. However, the study does demonstrate that there is a significant link between eating fruit and lowering diabetes risk. Hopefully more research will follow to confirm this.
It would make sense when you consider that whole fruits not only come with their natural sugars but also with fiber which helps to slow sugars down. Not to mention most juices (even 100% fruit juice), tends to be very concentrated.
To give you an example, 1 large orange has about 4g of fiber and 4tsp of sugar in it. One cup of orange juice on the other hand will have around 5 tsp of sugar and no fiber. Without that fiber the sugar has nothing to slow it down so it quickly enters your blood stream leading to a spike in your blood sugar. We also have to consider that many people will drink more than a measuring cup's worth of juice.
The moral of the story is eat your fruit instead of drinking it. It could do wonders for your health.