Judy Caplan, Nutrition & Dietetics, answered on behalf of Academy of Nutrition and Dietetics
Beans are by far the best plant source of protein. Although beans belong to the same plant family, they do come in a myriad of forms. Beans are a boon to diabetics because they are digested slowly causing a slow rise in blood sugar. In fact diabetics who eat lots of beans may need less insulin to control their blood sugar. Beans are full of energy giving complex carbohydrates, B vitamins, potassium, magnesium, calcium, zinc, and iron. The protein in beans unlike animal protein is fat free and generally high in fiber.