ABSTRACT
In the context of diabetes, the use of cinnamon continues to be among the most popular supplements taken by patients for glucose control. To strategically evaluate the available literature comparing various cinnamon species and statistically significant glucose effects after ranking studies based on two tools to assess bias and overall study quality, to clarify cinnamon's role in glucose control. The authors performed a systematic search based upon PRISMA guidelines. The search was conducted utilizing PubMed, AMED, CINAHL, EMBASE, Cochrane, and Medline databases, with the final search performed in September 2022 with restrictions to human subjects and English language. Electronic searches were conducted utilizing the keywords "diabetes mellitus" combined with Cinnamomum zeylanicum/Cinnamomum cassia/Cinnamomum verum combined with blood glucose (BG). A second search utilized "cinnamomum zeylanicum/cinnamomum cassia/cinnamomum verum" combined with "blood glucose," and a final search utilized "diabetes mellitus" combined with "cinnamon." Data extraction and ranking of included studies utilizing the risk of bias 2 tool and modified Heyland Methodological Quality Scoring tool were performed independently by two review authors. These authors compared their results and reconciled any differences in scoring to generate a final ranking of studies. A third author was available for any discrepancies that could not be resolved but was not needed. Forty-five studies were included in the review and were scored for bias and quality. Overall 62% demonstrated statistical significance for positive effects in at least one parameter around BG control. Applying the ranking systems reduced the percentage closer to 50%. Safety was extremely well documented across studies with few adverse effects. Results are limited by heterogeneity of glucose parameters, leading to studies being ranked individually and not synthesized. Cinnamon supplementation likely has a modest positive effect on BG. Based upon the strong safety profile, utilization of this spice as an adjunct to pharmacologic therapy is reasonable.
ABSTRACT
Cinnamon is a spice that has been used in various cultures for centuries for its potential health benefits. While there are health claims for a variety of health conditions, it has continuously been explored for its ability to improve glucose handling in diabetes. Cinnamon is a very popular supplement used by patients with diabetes to help normalize blood glucose levels. A systematic review of the literature was conducted to assess the available evidence evaluating effects on diabetes and glucose handling with the use of various species of cinnamon. The intention was to summarize the existing evidence for cinnamon's effects on blood glucose, both for safety and efficacy, to help guide providers and consumers alike. Reviewing the available literature for the different types of cinnamon and their effects on the diabetes disease process, there are multiple proposed mechanisms for how cinnamon could improve diabetes, including increasing insulin sensitivity by multiple receptor signaling pathways, reducing inflammation, enhancing glucose uptake by effects on glucose transporter proteins, and effects on gastric emptying, and blocking glucose absorption. There appears to be conflicting evidence on whether cinnamon produces any significant effect on glucose parameters, and the extent of these effects. There are several variables that could explain these conflicting data, such as patient sample size, doses and formulations of cinnamon used, baseline patient characteristics, and study duration. A more in-depth evaluation and rating of the available evidence could help clarify this, but data suggest that in some circumstances, cinnamon may have modest effects on improving glucose handling in adults. The safety profile also has been demonstrated to be extremely favorable, with very few adverse events reported in the active treatment groups across all studies. Based upon these data, clinicians should consider cinnamon to be a potential adjunctive therapy to traditional diabetes treatments, and should be open to discussing this with patients expressing interest in the supplement.
