Do Cinnamon Supplements Have a Role in Glycemic Control in Type 2 Diabetes?
Authors: Costello Rebecca B. , Dwyer Johanna T. , Saldanha Leila G. , Bailey Regan L. , Wambogo Edwina 
Published: November 2023

Management of type 2 diabetes mellitus (T2DM) emphasizes glucose control with diet, hypoglycemic drugs, lifestyle modification, and reduction in cardiovascular risk factors. In 2011–12, the estimated prevalence of T2DM in U.S. adults was 12.4%, up from 10.8% in 2001–2. Recently, cinnamon (Cinnamomum sp.) has been suggested to help T2DM patients achieve better glycemic control; however, conclusions from meta‐analyses on the question are mixed. It is difficult to disentangle effects due to cinnamon alone or to concurrent treatment with other therapies/modalities that patients are also receiving. To evaluate whether the use of cinnamon dietary supplements by adults with T2DM had clinically meaningful effects on glycemic control as measured by changes in fasting plasma glucose (FPG) or hemoglobin A1c (HbA1c), a comprehensive systematic PubMed literature search was performed from 01/01/1994 through 12/31/2014 using the following search terms: cinnamon, blood glucose, blood sugar, glucose metabolism disorders, or metabolic syndrome, diabetes, clinical trial, randomized clinical trial, systematic review, and meta‐analysis. Trials that enrolled exclusively T1DM were excluded as well as trials lacking a comparator or control group. Eight RCTs (two with dose titration arms) were identified that met our inclusion criteria enrolling 428 adult subjects with T2DM from 4 to 16 weeks in duration. Only 5 studies were double‐blinded. All studies enrolled patients on hypoglycemic medications and other interventions. Cinnamon doses ranged from 120 to 4500 mg/d, and seven studies used C. cassia/C. aromaticum; one study did not disclose the species of cinnamon. Only 2 studies achieved American Diabetes Association treatment goals (FPG <7.2 mmol/L or <130 mg/dL and/or HgAlc <7.0%), but levels in those two studies were only mildly elevated at baseline. All 8 studies reported reductions in FPG with cinnamon depending on baseline levels (p<0.0002). Six of 8 studies measured HgA1c, but percentage‐wise reductions were not as marked as those for FPG (p<0.02). Three studies showed reductions of ≥ 0.5% in HgA1c. When compared to placebo (between group comparisons), neither FPG nor HgA1c were significant. Collectively, the data suggest that cinnamon supplementation, when added to standard hypoglycemic medications and other lifestyle therapies had, at best, modest effects on FPG and HgA1c. Notably lacking in the description of patient groups was information on their weight status, any changes over the course of the study, and adherence to hypoglycemic medications, diet, or physical activity that might have had independent effects on the apparent ability of cinnamon to enhance glycemic control. There was variation in the form in which cinnamon was administered; extracts (aqueous and/or organic solvent extraction) and powders (pulverized bark material) ‐ each provide different compounds with different levels of bioavailability, making comparisons across studies difficult. Larger, high quality RCTs are needed in well‐defined population groups utilizing standardized interventions in order to definitively determine the efficacy of using cinnamon in subjects with diabetes.Support or Funding InformationFunding: Office of Dietary Supplements, National Institutes of Health