This randomised single-blinded clinical trial compares the efficacy of cinnamon, in capsules and as a powder in water, to prevent blood sugar spikes after a meal.
In this article, we discuss the “Suppression of the postprandial hyperglycaemia in patients with type 2 diabetes by a raw medicinal herb powder is weakened when consumed in ordinary hard gelatin capsules: A randomized crossover clinical trial” (1).
Plant name and species
Cinnamon (Cinnamomum cassia)
Aim of study
To examine a single dose of cinnamon powder dissolved in water versus cinnamon in gelatin capsules. Tests were made on postprandial hyperglycaemia in patients with type II diabetes.
Study method
Randomised, cross-over, single-blinded. Nineteen patients were randomised into five groups, all receiving a standardised meal on the day they visited the lab. These were meal alone (control), or ingestion prior to meal of 3 g cinnamon in capsules, 6 g cinnamon in capsules, 3 g cinnamon dissolved in water or 6 g cinnamon dissolved in water. There was a washout of 3–10 days between lab visits. The meals and cinnamon were all consumed within 15 minutes. Patients were not blinded but researchers involved were.
Blood glucoses responses were measured using a finger-prick blood sample and a glucometer.
Herbal preparation
Raw cinnamon powder was made into gelatin capsules or mixed with 150 ml of water (temperature of water not stated).
Sample size
Nineteen patients were randomised into the five groups in a cross-over design. Patients were all male with an average age of 56 years.
Results of study
Blood glucose peaks (spikes)
Ingestion of cinnamon capsules at 3 g did not alter postprandial glucose peaks, but 3 g of cinnamon in water led to a significant reduction (p=0.003). Both 6 g in capsules and water significantly reduced postprandial glucose levels.
Change in one-hour blood glucose
The change in blood glucose (from fasting levels) over one hour showed a similar pattern of results.
In the results, they also looked at absolute values and plotted these against accepted renal thresholds that are used to diagnose type II diabetes and administer insulin.
The mean highest blood glucose level
In this plot, a similar pattern of results was seen with 3 g cinnamon in water significantly reducing the highest blood glucose level, but 3 g in gelatin capsules being ineffective. The 3 g and 6 g cinnamon in water, and 6 g gelatin capsule reduced the glucose response to below the value of 200 mg/dL, which is a one-hour threshold used to diagnose diabetic disease.
In another variation of the results, the (absolute) one-hour post-meal mean blood glucose level showed a similar pattern.
The time to reach peak glucose is also a marker of insulin resistance, and is usually longer in diabetic patients. There was no difference between any of the groups.
In terms of palatability and sensory experience, raw cinnamon powder in capsules or water did not differ in terms of visual appeal, smell and taste.
Discussion
Raw cinnamon powder in water decreased glucose spikes following a meal, whereas cinnamon in gelatin capsules was less effective, with responses not significant in the 3 g capsule group. When looking at absolute values, cinnamon reduced post-meal glucose away from harmful thresholds, leading the authors to conclude that the spice —particularly in water — has potential as a diabetes treatment. There was no change in time-to-peak which is an indicator of insulin resistance.
The effects are attributed to the high fibre content, and cinnamon is about 50% fibre, which is mainly insoluble. It is well established that fibre can inhibit carbohydrate digestion, with many studies done on wheat bran, cellulose and cinnamon. So, the differences observed in this study may be that cinnamon given in water may have acted quickly and directly to reduce amylase activity in the mouth and small intestine, whereas the gelatin capsule would have taken more time to dissolve, and also would not have acted in the mouth.
Also, cinnamon consists of a host of compounds including oils of which cinnamaldehyde is the most abundant and contributes to the sweet and spicy taste. Other oils include eugenol, but compositions vary across cinnamon species and parts of the tree used (bark or leaf). It has been shown that cinnamon oil can improve glucose, lipid and insulin biomarkers, and also modulate gene expression to favour antidiabetic outcomes, although this research is mainly in animals (2). Therefore, other antidiabetic actions may be attributed to the constituents of the spice.
In the paper, the authors describe in vitro studies, which suggest that cinnamon may also act directly on isolated insulin-secreting cells and alter glucose transporter (GLUT-4) activity and other molecular signals that lead to insulin secretion; but, consuming cinnamon does not result in hypoglycaemia, so it is possible that this is not a mechanism that plays out within the body.
The authors suggest that the advantage of cinnamon powder in water is a more direct ingestion of the plant, and that all results were weakened with the gelatin capsule formulations. They cite other studies that have found that gelatin takes a while to disintegrate and the active ingredients can have reduced biological effects when taken in capsule form.
Further research could explore the benefits of taking cinnamon in water before a meal, and what the longer-term benefits of reducing hyperglycaemic spikes might be in diabetic patients. People may be tempted to take cinnamon as a tea, so the impact of water temperature on the volatile oils and other constituents needs further study. Studies should note the species of cinnamon and parts of the plant used.
Conclusion
A single dose of 3 g raw cinnamon powder dissolved in water given before a meal reduced glucose spikes and postprandial hyperglycaemia in patients with type II diabetes. Therefore, cinnamon holds promise in offering a simple and accessible therapy to support the rising tide of diabetes.
References
- Moreira, F. D., Reis, C. E. G., Gallassi, A. D., Moreira, D. C., & Welker, A. F. (2024). Suppression of the postprandial hyperglycemia in patients with type 2 diabetes by a raw medicinal herb powder is weakened when consumed in ordinary hard gelatin capsules: A randomized crossover clinical trial. PloS one, 19(10), e0311501. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0311501
- Stevens, N., & Allred, K. (2022). Antidiabetic potential of volatile cinnamon oil: A review and exploration of mechanisms using in silico molecular docking simulations. Molecules, 27(3), 853. https://pmc.ncbi.nlm.nih.gov/articles/PMC8840343/
