The effect of cinnamon supplementation on glycemic control in patients with type 2 diabetes or with polycystic ovary syndrome: an umbrella meta-analysis on interventional meta-analyses.
Level 1 - systematic review of randomized trials
Umbrella meta-analysis of meta-analyses of randomized controlled trials
PubMed 37316893 · doi:10.1186/s13098-023-01057-2
What was done
Authors conducted an umbrella meta-analysis synthesizing existing meta-analyses of randomized controlled trials (RCTs) searched across PubMed, Scopus, EMBASE, Web of Science, and Google Scholar up to June 2022. The review assessed the effects of cinnamon supplementation on glycemic indices—fasting plasma glucose (FPG), insulin, homeostatic model assessment for insulin resistance (HOMA-IR), and HbA1c—in patients with type 2 diabetes (T2D) or polycystic ovary syndrome (PCOS). Random-effects models were used to pool weighted mean differences (WMD) and standardized mean differences (SMD) with 95% confidence intervals (CI).
What was found
Eleven meta-analyses of RCTs were included. Cinnamon supplementation significantly reduced: - FPG: WMD -10.93 mg/dL (95% CI: -16.22, -5.65); SMD -0.86 (95% CI: -1.19, -0.52) - Insulin: WMD -2.01 IU/mL (95% CI: -3.96, -0.07); SMD -0.61 (95% CI: -0.93, -0.30) - HOMA-IR: WMD -0.61 (95% CI: -0.91, -0.31); SMD -0.78 (95% CI: -1.26, -0.30) - HbA1c: WMD -0.10% (95% CI: -0.17, -0.03)
Why it matters
This review synthesizes conflicting previous meta-analyses to confirm statistically significant glycemic-lowering effects of cinnamon in insulin-resistant populations. However, the absolute clinical reduction in HbA1c (-0.10%) is very small.
Limits
The abstract pools T2D and PCOS populations without reporting stratified results by disease. Umbrella reviews risk double-counting primary RCTs included across multiple meta-analyses. Total participant count, cinnamon species, dosing, duration of intervention, adverse effects, and heterogeneity metrics are not reported in the abstract.
Cited by
- supports Cinnamon decreases and improves insulin resistance.