Influence of Cinnamon on Glycemic Control in Individuals With Prediabetes: A Randomized Controlled Trial

A Randomized Controlled Trial

Giulio R. Romeo; Junhee Lee; Christopher M. Mulla; Youngmin Noh; Casey Holden; Byung-Cheol Lee


J Endo Soc. 2020;4(11) 

In This Article

Abstract and Introduction


Context: The identification of adjunct safe, durable, and cost-effective approaches to reduce the progression from prediabetes to type 2 diabetes (T2D) is a clinically relevant, unmet goal. It is unknown whether cinnamon's glucose-lowering properties can be leveraged in individuals with prediabetes.

Objective: The objective of this work is to investigate the effects of cinnamon on measures of glucose homeostasis in prediabetes.

Design, Setting, Participants, and Intervention: This double-blind, placebo-controlled, clinical trial randomly assigned adult individuals meeting any criteria for prediabetes to receive cinnamon 500 mg or placebo thrice daily (n = 27/group). Participants were enrolled and followed at 2 academic centers for 12 weeks.

Main Outcome Measures: Primary outcome was the between-group difference in fasting plasma glucose (FPG) at 12 weeks from baseline. Secondary end points included the change in 2-hour PG of the oral glucose tolerance test (OGTT), and the change in the PG area under the curve (AUC) derived from the OGTT.

Results: From a similar baseline, FPG rose after 12 weeks with placebo but remained stable with cinnamon, leading to a mean between-group difference of 5 mg/dL (P < .05). When compared to the respective baseline, cinnamon, but not placebo, resulted in a significant decrease of the AUC PG (P < .001) and of the 2-hour PG of the OGTT (P < .05). There were no serious adverse events in either study group.

Conclusions: In individuals with prediabetes, 12 weeks of cinnamon supplementation improved FPG and glucose tolerance, with a favorable safety profile. Longer and larger studies should address cinnamon's effects on the rate of progression from prediabetes to T2D.


Diabetes affects more than 460 million adults globally[1] and is the seventh leading cause of disability worldwide,[2] accounting for more than $320 billion in health care costs in the United States alone.[3] The rise in prevalence of diabetes over the past 3 decades, primarily type 2 diabetes (T2D), has occurred at a particularly fast rate in East and South Asia.[4]

Using current diagnostic criteria set forth by the American Diabetes Association,[5] approximately 38% of the US population has prediabetes,[6] which remains unrecognized in the vast majority of cases.[7] Prediabetes portends an annual progression to T2D ranging from 3% to 11% depending on the population.[8–10] The rate of incident T2D is higher in individuals with impaired glucose tolerance (IGT) who are also at increased risk of cardiovascular disease, as compared to patients with impaired fasting glucose (IFG).[11,12]

As previously reviewed,[13] the conversion from prediabetes to T2D can be effectively prevented using lifestyle modifications,[9,14–16] antidiabetic drugs,[9,16–19] weight loss medications,[20] and metabolic surgery.[21,22] However, such approaches to T2D prevention have several limitations. First, long-term follow-up, which is available for only a subset of interventions, demonstrates a progressive attenuation of benefits on T2D conversion rate over time.[23–25] In addition, both the cost and potential side effects (eg, weight gain with pioglitazone) can limit adherence to drugs longitudinally. Finally, up to 50% of at-risk patients will develop T2D even within the structured framework of randomized clinical trials (RCTs).[13] Therefore, identification of efficacious, durable, safe, and cost-effective strategies for T2D prevention remains a clinically relevant unmet need, especially in low- and middle-income countries.

Complementary and alternative medicine practices, including the use of nutraceuticals, have flourished over recent decades. Based on a 2012 National Health Interview Survey, 18% of adults in the United States had used a nonvitamin, nonmineral dietary supplement during the past year.[26] Approximately one-third of patients with T2D have used complementary and alternative medicine, either alone or as adjunct, for treatment of this condition. The evidence for safety and efficacy of nutraceuticals in T2D treatment is sparse and in many instances of low quality.[27,28]

Extracts of the inner bark of the Cinnamomum genus ("cinnamon") of aromatic trees, commonly used as flavoring agents, have been employed since ancient times for treating arthritis and other inflammatory diseases,[29] and are currently marketed as therapeutic supplements for T2D. In experimental models of diabetes, mechanisms invoked for the glucose-lowering activity of cinnamon include increased glucose transporter type 4 (GLUT4) membrane translocation,[30] stimulation of postprandial levels of glucagon-like peptide-1,[31] inhibition of α-glucosidase activity,[32] and antioxidant properties.[33]

Several RCTs in adult patients with T2D have addressed the effects of various powdered monopreparations of cinnamon, predominantly Cinnamomum cassia, on changes in glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), and lipid profile.[34,35] The duration of these studies ranged from 4 weeks to 4 months with daily dosages of compounded cinnamon varying from 500 mg to 6000 mg. Notwithstanding significant heterogeneity in study design, the majority of RCTs demonstrated a 10% to 15% reduction in FPG from baseline whereas changes in HbA1c were inconsistent and did not reach statistical significance in the aggregate.[35] Cinnamon's beneficial effects were more pronounced in drug-naive patients than as add-on therapy, and in patients with high baseline HbA1c (> 8%).[34]

In individuals with prediabetes, the evidence from RCTs addressing the impact of cinnamon on glucose homeostasis is more limited. Specifically, it remains unclear whether in this population: a) cinnamon affects FPG, glucose tolerance, or both, and b) the response to cinnamon is conserved across ethnic groups.

Here, we present the results of efficacy and safety in a 2-country, placebo-controlled RCT of cinnamon treatment conducted in participants with prediabetes.