It’s not yet clear if cinnamon is good for reversing/preventing diabetes. (One gram of ground cinnamon is about half a teaspoon.)

Some researchers found cinnamon cut cholesterol by about 18% and blood sugar levels by 24%. But in other studies, the spice did not lower blood sugar or cholesterol levels. Ceylon cinnamon, a more rare yet more potent cinnamon variety, can provide optimal benefits with minimal risk (except for cost).

References

Pearson, Keith, PhD, RD. “How Cinnamon Lowers Blood Sugar and Fights Diabetes,” Healthline (March 22, 2017). https://www.healthline.com/nutrition/cinnamon-and-diabetes (accessed on 8/3/2020).

Benson, Jonathan, staff writer. “Ceylon cinnamon lowers blood sugar better than drugs: Study,” Natural News (January 12, 2014). https://www.naturalnews.com/043477_Ceylon_cinnamon_blood_sugar_levels_diabetes_treatment.html# (accessed on 8/3/2020).

Can You Lower Blood Sugar with Cinnamon?
https://www.peoplespharmacy.com/2017/05/22/can-you-lower-blood-sugar-with-cinnamon/

Cinnamon and Diabetes
https://www.webmd.com/diabetes/cinnamon-and-benefits-for-diabetes

Cinnamon and Diabetes: An Update
https://www.diabetesselfmanagement.com/blog/cinnamon-and-diabetes-an-update/

Cinnamon, blood sugar, and diabetes
https://www.medicalnewstoday.com/articles/317207

Does Cinnamon Help Diabetes?
https://www.webmd.com/diabetes/cinnamon-and-benefits-for-diabetes

The Cinnamon and Diabetes Connection
https://www.sepalika.com/type-2-diabetes/cinnamon-and-diabetes/

Which Cinnamon Is Better for Blood Sugar?
https://www.peoplespharmacy.com/2016/08/01/which-cinnamon-is-better-for-blood-sugar/