The effect of cinnamon supplementation on glycemic control in patients with type 2 diabetes mellitus: An updated systematic review and dose‐response meta‐analysis of randomized controlled trials

Abstract

Although many randomized controlled trials (RCTs) have revealed the benefits of cinnamon on type 2 diabetes mellitus (T2DM), the effects of cinnamon supplementation on glycemic control in patients with T2DM are inconclusive. Therefore, the aim of this meta‐analysis of RCTs was to assess the effects of cinnamon supplementation in managing glycemic control in patients with T2DM. Scientific international databases including Scopus, Web of Sciences, PubMed, Embase, and the Cochrane Library were searched till December 2022. For net changes in glycemic control, standard mean differences (SMDs) were calculated using random‐effects models. Findings from 24 RCTs revealed that cinnamon supplementation had a statistically significant reduction in fasting blood sugar (SMD: −1.32; 95% CI: −1.77, −0.87, p < 0.001), Homeostatic Model Assessment for Insulin Resistance (SMD: ‐1.32; 95% CI: −1.77, −0.87, p < 0.001), and hemoglobin A1C (SMD: −0.67; 95% CI: −1.18, −0.15, p = 0.011) compared with the control group in patients with T2DM. Additionally, cinnamon did not change the serum levels of insulin (SMD: −0.17; 95% CI: −0.34, 0.01, p = 0.058) significantly. Our analysis indicated that glycemic control indicators are significantly decreased by cinnamon supplementation. Together, these findings support the notion that cinnamon supplementation might have clinical potential as an adjunct therapy for managing T2DM.

Potential Benefit of Spices for Glycemic Control

“…The authors suggested that use of water extracts might be preferable to whole cinnamon in interventions as a way to avoid intake of constituents in whole cinnamon sometimes associated with possible deleterious effects. Another meta-analysis of 24 RCTs 45 determined that C cassia possessed more hypoglycemic properties compared with C verum . Of note, several analyses 33,38,43–45 observed a somewhat paradoxical effect of cinnamon on glycemic markers.…”

“…Another meta-analysis of 24 RCTs 45 determined that C cassia possessed more hypoglycemic properties compared with C verum . Of note, several analyses 33,38,43–45 observed a somewhat paradoxical effect of cinnamon on glycemic markers. In other words, a benefit was more prominent at lower doses (≤1.2–3 g/d) compared with higher intakes.…”

“…The species of cinnamon plant used in RCTs was not always clearly described. Most meta-analyses observed a statistically significant reduction (Table 2) in FBG values following intake of cinnamon, [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] compared with controls. Statistically significant decreases in HbA 1c and fasting serum insulin (SI) values and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) measures for those administered cinnamon, compared with controls, were variable.…”

“…In one meta-analysis, 37 subgroup examination determined that the water extract retained similar FBG-lowering activity compared with powdered bark. The authors suggested that use of water extracts might be preferable to whole cinnamon in interventions as a way to avoid 33,38,[43][44][45] observed a somewhat paradoxical effect of cinnamon on glycemic markers. In other words, a benefit was more prominent at lower doses (≤1.2-3 g/d) compared with higher intakes.…”

Herbal Products as Complementary or Alternative Medicine for the Management of Hyperglycemia and Dyslipidemia in Patients with Type 2 Diabetes: Current Evidence Based on Findings of Interventional Studies

“…Several studies indicated the improving effect of cinnamon on glycemic indicators in patients with T2D [ 29 ]. Based on Mang et al, after four months of supplementation with a purified aqueous cinnamon extract, a 10.3% reduction in fasting plasma glucose was observed [ 30 ].…”