Diabetes Management: Bitter gourd or karela is a tropical vegetable which is rich in fiber, vitamin C, vitamin A, folate, iron and zinc. You might not like the bitter taste of this veggie, but did you know that karela actually has got multiple health benefits, especially for diabetes. Bitter gourd can be used to cure diabetes. There are many ways in which you can use karela for managing your blood sugar levels. It contains active substances like polypeptide and vicine that improves the ways your tissues use sugar, promotes secretion of insulin there by naturally lowering blood sugar level.