Raspberries, strawberries and blueberries contain the lowest amount of sugar per 1/2 cup compared to other fruits. The majority of carbohydrates contained in berries are starch, making berries a good, low-sugar food.
Fruit with less than 10 grams of sugar per 1/2 cup are considered low in sugar. For comparison, a banana contains 14.4 grams of sugar per 1/2 cup and a mango contains 23 grams. Though not typically considered a fruit, tomatoes and avocados are two fruits with very low sugar contents. Generally, the sweeter tasting a fruit is, the more sugar it contains. Bitter and sour fruits such as cranberries, lemons and lime are also low-sugar fruits.