Experts including a team at Harvard School of Public Health in the US examined if certain fruits impact on type 2 which affects more than 210,000 Scots.
People who ate three standard servings a week of blueberries had a 26% lower chance of developing the disease, they found. Those eating grapes and raisins had a 12% reduced risk and apples and pears cut the chances by 7%. Prunes also had a protective effect, giving an 11% drop in the risk of developing type 2 diabetes, which is often linked to obesity.
Other fruits such as bananas, plums, peaches and apricots had a negligible impact but drinking fruit juice increased the risk by 8%, according to the study.
In fact, people who replaced all fruit juice with eating whole fruits could expect a 7% drop in their risk of developing type 2.
The research, published in the British Medical Journal, included data on 187,382 people taken from three separate studies, of whom 12,198 developed type 2 diabetes.
The relatively high glycaemic load of fruit juice along with "reduced levels of beneficial nutrients through juicing processes" may explain why juice increases the risk of type 2 diabetes, the authors suggest.
"Fluids pass through the stomach to the intestine more rapidly than solids even if nutritional content is similar. For example, fruit juices lead to more rapid and larger changes in serum levels of glucose and insulin than whole fruits," they said.