Cinnamon Supplements Show Promise for Delaying Conversion to Type 2 Diabetes

Giulio Romeo, MD

New research from a double-blind, placebo-controlled trial suggests supplemental cinnamon could improve fasting plasma glucose and glucose tolerance among patients with prediabetes.

Conducted by an international team of investigators, results of the 12-week study indicate cinnamon could be a durable, cost-effective approach to reducing progression from prediabetes to type 2 diabetes.

"Our 12-week study showed beneficial effects of adding cinnamon to the diet on keeping blood sugar levels stable in participants with prediabetes," said study investigator Giulio R. Romeo, MD, staff physician at Joslin Diabetes Center in Boston, in a statement. “These findings provide the rationale for longer and larger studies to address if cinnamon can reduce the risk of developing type 2 diabetes over time."

With experimental models indicating cinnamon could have glucose-lowering and other therapeutic effects, investigators sought to determine the effects of cinnamon on measures of glucose homeostasis in prediabetes. To investigate these effects, Romeo and colleagues designed their study as a double-blind, placebo-controlled clinical trial randomizing adults with prediabetes to receive 500 mg of cinnamon or placebo 3 times per day for 12 weeks.

Participants in the study were recruited from the Kyung Hee University Medical Center and the Joslin Diabetes Center between 2017-2018. To be included, participants needed to be between the ages of 20-70 and demonstrate 1 of 3 specific abnormalities. Abnormalities were defined as impaired fasting glucose, impaired glucose tolerance, and an HbA1c level of 5.7-6.4%.

Of note, patients were excluded if they had evidence of diabetes mellitus or other significant endocrine, cardiovascular, pulmonary, renal, or liver disease. Additional exclusion criteria included pregnancy, intentional weight loss of 10 or more pounds in the preceding 6 months, therapy with corticosteroids, or use of any drug or supplement with glucose-lowering effects.

The primary end point of the study was the between-group difference in fasting plasma glucose at 12 weeks from baseline. Secondary end points included change in 2-hour prandial glucose and the change in prandial glucose area under the curve, which were both based on measurements from an oral glucose tolerance test (OGTT).

Patients randomized to cinnamon received cinnamon capsules containing 300 mg of cinnamon extract and 200 mg of cinnamomum burmannii powder. The placebo capsule was 91.5% cellulose, 8.4% caramel food coloring, and 0.1% cinnamon incense.

In total, 50 participants were screened, 54 participants were enrolled, and 51 participants completed the study. Of the 51 participants who completed the study, 24 had been randomized to cinnamon and 27 had been randomized to placebo. Investigators pointed out baseline characteristics were similar between the treatment arms.

Upon analysis, investigators found changes in fasting plasma glucose levels were not different between the 2 groups at 6 weeks. Conversely, 12-week assessments indicated fasting glucose rose after 12 weeks with placebo, yielding a mean between-group difference of 5 mg/dL (114±8 vs 108±11; P <.01).

When examining secondaryend points, results indicated cinnamon was associated with a significant reduction in the area under the curve of plasma glucose during the OGTT from baseline to 12 weeks (21,389±3858 vs 19946 ± 4070 mg/dL/120 min; P <.05). In comparison, no change was observed among patients in the placebo group. Additionally, cinnamon was associated with a significant decrease in plasma glucose at the 2-hour time point of the OGTT from baseline to 12 weeks (-20±27 mg/dL; P <.01).

Investigators also pointed out no adverse events were observed in either study group during the 12-week study period.

This study, “Influence of cinnamon on glycemic control in subjects with prediabetes: a randomized controlled trial,” was published in the Journal of the Endocrine Society.