Black grapes can be a healthy food choice for diabetics, but they should be consumed in moderation as they contain natural sugars. Black grapes are high in antioxidants, vitamins, and minerals, which can benefit overall health. They are also low in glycemic index, which means they do not cause a rapid increase in blood sugar levels. However, diabetics should still monitor their carbohydrate intake and overall diet to maintain stable blood sugar levels. It is best to consult with a healthcare professional or registered dietitian for personalized dietary recommendations.