Background and aims: There is some evidence regarding the positive effects of cinnamon on metabolic status in patients with type 2 diabetes (T2DM). However, they are conflicting. In the present study, we aimed to systematically review the effects of cinnamon on glycemic status and anthropometric indices in patients with T2DM.
Methods: Five electronic databases including PubMed/Medline, SCOPUS, Web of Sciences, EMBASE, and the Cochrane library were searched until 31 February 2018 with no language limitation. Randomized clinical trials that examined the effects of cinnamon on at least fasting blood sugar (FBS) were included. Other glycemic parameters and anthropometric indices were also extracted. A random effects model with DerSimonian and Laird method was used for pooling the effect sizes.
Results: Finally, 18 studies were included in the meta-analysis. Supplementation with cinnamon reduced FBS by -19.26 mg/dL (95% CI: -28.08, -10.45; I2:96.5%; p = 0.0001) compared to placebo. However, the effects of cinnamon on HbA1C (-0.24%; 95% CI: -0.48, -0.01; I2: 76.8%, p = 0.0001), body weight (-0.46, 95%CI: -1.87, 2.30; I2:0%; p = 0.79), body mass index (WMD: -0.05 kg/m2; 95% CI: -0.52, 0.42; I2: 0%; p = 0.91), and waist circumference (WMD: -0.53 cm; 95% CI: -3.96, 2.81; I2: 0%; p = 0.66) were not significant. Additionally, cinnamon did not change the serum levels of insulin and insulin resistance significantly.
Conclusion: Supplementation with cinnamon can reduce serum levels of glucose with no changes in other glycemic parameters and anthropometric indices. However, due to high heterogeneity findings should be interpreted with great caution.
Keywords: Cinnamon; Glycemic parameters; Metabolic status; T2DM.
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