Yes.
The answer to this question is yes, black plums have carbs. Black plums are rich in sugar and starch, making them 55% sugar by weight! Six of them can contain up to 22 grams of carbohydrate content. Although they don’t provide the same high levels of glucose as some other foods (such as white rice), they still do contain carbohydrates nonetheless, which will need to be dealt with on a diet like keto or paleo.