To what extent does cinnamon administration improve the glycemic and lipid profiles?

Background & aims: Cinnamon is a condiment used in cooking and by some in large quantities as a supplement with purported hypoglycemic and lipid-lowering potential. The current literature review aims to discuss the evidence of cinnamon administration regarding its hypoglycemic and lipid-lowering effects, summarizing clinical recommendations.

Methods: Electronic databases including PubMed, Cochrane library, Science Direct and Web of Science were searched with the scientific name of the plant as well as the common name. The search for articles was based on following keywords: "cinnamon diabetes", "cinnamon diabetes type 2", "cinnamon and diabetes type 2", "Cinnamomum aromaticum", "Cinnamomum cassia", "Cinnamomum verum", "Cinnamomum zeylanicum". We carried out inclusion criteria between 2003 and 2018 focusing on human studies.

Results: Concerning glycemic profile, in individuals with type II diabetes mellitus the fasting blood glucose reduced from 12.9 to 52.2 mg/dL and HbA1c from 0.27 to 0.83%, whereas serum insulin decreased in few studies. Research papers ranged from 6 to 17 weeks in duration. The lipid lowering potential, in turn, is most controversial compared to anti-hyperglycemic potential. Also cinnamon administration has been claimed to reduce fat mass and raise serum antioxidants, but the studies used inaccurate methods. Two species are most investigated, C. cassia/aromaticum, and C.zeylanicum/verum.

Conclusions: About 1-6 g of these cinnamon species mainly in powder seems to be an adjunct drug treatment for type 2 diabetes mellitus and other conditions of glycemic impairment. However, more controlled clinical trials are needed.