These days, diabetics aren't restricted to the dietary limitations of prior years, and eating fruits such as raisins is completely acceptable even when you're trying to control your blood sugar levels. The key is to balance your intake of carbohydrates with fat and protein to prevent major blood glucose fluctuations.
If you're following a carbohydrate exchange meal plan to help control your diabetes, 2 tablespoons of raisins count as a single carbohydrate exchange, or approximately 15 grams of carbohydrates. You can use one serving of raisins in place of any other carbohydrate source in a given meal, such as a 15-gram serving of grains, starch or dairy.
Raisins have a low to moderate glycemic index, so a single serving does not impact blood sugar levels as much as many other carbohydrates. However, because raisins are small, it's easy to eat multiple servings in a single sitting. Stick with just one serving at a time.