Yes, why not type-2 diabetes people can eat apples but quantity does matters. In fact apple is very nutritious is rich source of iron, vitamins, potassium, vitamin A. It is This food is very low in Saturated Fat, Cholesterol and Sodium. It is also a good source of Dietary Fiber and Vitamin C.
In diabetes it is myth that diabetic people should not eat Apple (sweet fruits). Fact is that total amount of carbohydrate in a food affect blood sugar is more than other sources of carbohydrate like sugar. For diabetic people one serving of fruit should contain 15 gm carbohydrate. The size of the serving depends on the carbohydrate content of the fruit. If some fruit contains less carbohydrate then that can be eaten in more quantity.
An medium size apple contains about 15 gm carbohydrate so people with type- diabetes can eat a apple.
Above is estimated quantity of carbohydrate in Apple and using this you can calculate how much Apple can be eaten by type-2 diabetic person in a day.
For 15 gm carbohydrate intake 1 medium size fresh Apple will be sufficient. So you can eat a medium size apple . but you have to cut other carbohydrate intake to balance your diet.