In this randomized, crossover study, 30 men and women, ages 18-30 years, were given one of two test meals: plain hot cereal or hot cereal with cinnamon. Participants were tested two times, receiving each breakfast once. Blood samples were taken seven times over a two-hour period after the start of the meal. The addition of cinnamon to the cereal helped to flatten the glycemic response and reduce fluctuations in blood glucose in both the normal weight and obese study participants during the time following the meal.
Critical questions for future research, the authors wrote, are whether the reduction of blood glucose is maintained with long-term cinnamon supplementation and, if so, whether the reduction can delay or prevent the development of type 2 diabetes. They conclude that cinnamon “may offer nutrition and dietetics practitioners and their clients a unique botanical-based preventive approach to modify blood glucose.”
Source: Magistreilli A, Chezem JC. "Effect of Ground Cinnamon on Postprandial Blood Glucose Concentration in Normal-weight and Obese Adults." Journal of the Academy of Nutrition and Dietetics. 2012:112;1806-1809.