Ginseng: North American ginseng has been shown to improve blood sugar control and to elevate glycosylated hemoglobin levels (the hemoglobin the blood used to monitor blood glucose levels over time). Compare your results to a diabetic levels range chart to see if you’re in a healthy range. In a 2017 study, researchers looked into the effects of clove extract and nigricin, a compound found in cloves, on human muscle cells and diabetic mice.