Efficacy and Safety of Cinnamomum zeylanicum (Ceylon cinnamon) for diabetes mellitus: a randomized, double blind, placebo-controlled clinical trial.

2025-12-12
Diabetes & metabolic syndrome 19(12)
- Priyanga Ranasinghe
- Priyadarshani Galappatthy
- Godwin R Constantine
- Ranil Jayawardena
- Hasitha D Weeratunga
- Sirimal Premakumara
- Prasad Katulanda

PubMed: 41412108
DOI: 10.1016/j.dsx.2025.103357

Study Design

Type: Randomized Controlled Trial (RCT)
Sample size: n = 210
Population: 210 individuals with Type 2 Diabetes
Methods: Randomly assigned in equal numbers to two CZ extract groups (250 mg or 500 mg) and one placebo group
Duration: four months

Large Human Trial

Background

The search for novel antihyperglycemic agents from herbal medicines has highlighted cinnamon, which contains biologically active compounds with insulin-mimetic effects in-vitro. We assessed the efficacy and safety of Cinnamomum zeylanicum (CZ) extract in individuals with Type 2 Diabetes.

Methods

A total of 210 individuals with Type 2 Diabetes were randomly assigned in equal numbers to two CZ extract groups (250 mg or 500 mg) and one placebo group. The primary outcome was change in glycaemic control (HbA1c and fasting plasma glucose [FPG]) from baseline. Secondary outcomes included serum lipids, insulin resistance and β-cell function, systolic (SBP) and diastolic (DBP) blood pressure, and anthropometric parameters. Multiple regression analyses were conducted with change in FPG or HbA1c from baseline as the dependent variables and treatment group and covariates as predictors.

Results

The mean age of participants was 58.6 ± 8.2 years, with 42.9 % (n = 90) being male; 186 completed the four-month follow-up. Both FPG and HbA1c significantly declined in the CZ extract groups compared to baseline, accompanied by reduced insulin resistance and improved β-cell function (p < 0.05). At four months, total and LDL cholesterol were significantly lower in the 500 mg CZ extract group (p < 0.05). Regression analyses identified CZ extract treatment as a significant predictor of changes in both FPG and HbA1c.

Conclusions

This randomized controlled trial developed and tested a CZ-based intervention for Type 2 Diabetes, demonstrating its promising efficacy and safety. Further studies are warranted to explore its potential as a pharmaceutical agent for diabetes management.

Trial registration

Sri Lanka Clinical Trials Registry, identifier: SLCTR/2017/010 (http://slctr.lk/trials/714). Registered on April 05, 2017; Study protocol version 3.1 (March 21, 2017).