The Chinese mentioned cinnamon in their written work more than 4,000 years ago. The ancient Egyptians used cinnamon in their embalming process, and the Roman writer/philosopher Pliny the Elder wrote in the first century AD that cinnamon was worth 15 times more than silver of the same weight.

In Medieval times, physicians used cinnamon for such ailments as sore throats. Later, Portugal, Holland, France and England vied for ownership of the island of Ceylon (Sri Lanka), where the world’s cinnamon was grown. But those rivalries ended in the early 1800s when the cinnamon monopoly dissolved after it was discovered that the spice could be grown in many other areas.

In the West today when most people think of cinnamon they immediately think about that most unhealthy, but delicious, pastry, the cinnamon roll. However, in the past few years cinnamon has been making a comeback in its old “roll” as a medication. Is cinnamon a substance with medicinal properties germane to the treatment of hyperglycemia? If so, is it safe? If it is safe and effective, how and when should it be taken? These aforementioned questions are worth answering.

Cinnamon and Glucose

Several mechanisms by which cinnamon might lower glucose have been proposed. Cinnamon may have an insulin-like effect, causing glucose to be stored in the form of glycogen. In one study of rats, cinnamon reportedly caused an increase in a compound IRS-1, which is responsible for increasing glucose uptake in muscle tissue. Cinnamon has also been reported to cause an increase in the transporter mechanisms (GLUT-4) that take glucose out of the blood stream and into tissue. Cinnamon has also been cited as having a number of other properties that might contribute to any hypoglycemic effect that it might have.

Cinnamon and Diabetes

The most often-cited study on the effects of cinnamon and diabetes was published in the journal Diabetes Care in 2003 by Khan and colleagues. This study evaluated 60 people with type 2 diabetes around the age of 50. They were divided into six groups of 10 patients each. Groups 1 through 3 were treated with 1, 3, or 6 grams of cinnamon daily, respectively. Groups 4 through 6 received a placebo.

Treatment with cinnamon or placebo lasted for 40 days. Researchers analyzed both groups’ fasting glucose, LDL cholesterol, triglycerides and total cholesterol. No changes in the placebo group were observed over the 40-day period. However, in the cinnamon groups reductions in fasting glucose (down18 percent to 29 percent), triglycerides (down 23 percent to 30 percent), LDL cholesterol (down 7 percent to 27 percent) and total cholesterol (down 12 percent to 26 percent) were reported. If this were the end of the story, and if high-dose, long-term cinnamon was known to be safe, then perhaps cinnamon therapy would be widely recommended. Unfortunately, the picture is not quite so clear.

German Study Doesn’t Repeat Results

Another study carried out in Germany evaluated 65 patients with type 2 diabetes. This study was similar to the one above except half of the patients received placebo while the other half all received 3 grams of cinnamon daily for four months. In this study no difference between the two groups was reported for LDL or HDL cholesterol, triglycerides or HgbA1c. Fasting glucose levels dropped about 7 percent more in the group receiving cinnamon.

In the spring of 2006, another study of cinnamon appeared in the Journal of Nutrition. This study evaluated 25 post-menopausal women with type 2 diabetes who were treated with 1.5 grams of cinnamon daily for six weeks. Cinnamon was not associated with a significant change in insulin sensitivity, glucose tolerance or cholesterol profile.

Another study was published this year in the journal Diabetes Care. This study compiled all of the published human data from controlled studies of cinnamon and analyzed it together (a meta-analysis). This study concluded that cinnamon did not appear to improve HgbA1c, fasting glucose or blood lipids in patients with either type 1 or type 2 diabetes.

Should Cinnamon Be Recommended?

At this point the data regarding cinnamon’s efficacy in reducing glucose levels in patients with diabetes is inconsistent at best. Given the facts that hyperglycemia is a tissue toxic state and that safe and effective medications are available to reduce it, cinnamon should not be widely recommended at this time.

There are other concerns as well. Some forms of cinnamon contain a compound (coumarin) that can reduce the blood’s ability to clot. This has led authorities in Germany to seek reclassification of cinnamon supplements as regulated medication.

Cinnamon taken in supplemental doses should be avoided until more data is available and all safety concerns have been assuaged.

Sources:

• Baker et al. Effect of Cinnamon on Glucose Control and Lipid Parameters. Diabetes Care. 2008;31:41-3
• Khan A et al. Cinnamon Improves Glucose and Lipids in People with Type 2 Diabetes. Diabetes Care. 2003;26:3215-18
• Vanschoonbeek K et al. Cinnamon Supplementation Does Not Improve Glycemic Control in Postmenopausal Type 2 Diabetes Patients. Journal of Nutrition. 2006;136:977-980

Some Questions About This Article From Scott King, Editor-in-Chief:

John:

Thank you for this concise and accessible update to a topic that has been going around in the diabetes community for some time. I have some questions, though, about some of the studies you cited:

Did Khan use a different kind of cinnamon than other researchers to achieve results at such low dosages?

Why weren’t other researchers able to replicate his results?

Scott

Prof. White Replies:

Good questions. Khan used cinnamomum cassia and it was ground and added to flour and put into capsules. I don’t know about the other researchers decision making process regarding dose. Khan reported changes at 1, 3 and 6 grams so lower doses do seem reasonable.

Why weren’t others able to replicate the results? I don’t know. That is why clinical studies are repeated. Many things effect metabolic parameters. Just the fact that someone is in a study can cause changes (Hawthorne Effect). Anytime a natural substance is used there are myriad potential confounding factors. Additonally, there may be genetic factors among the patients.

In the final analysis, however, I think we have to look at all of the data. When we do this, it seems, at least at this point, that cinnamon has not been shown to be effective. Larger studies may prove this conclusion wrong.

I hope that helps. JW

John R. White, Jr., PA, PharmD, is a professor in the Department of Pharmacotherapy at the College of Pharmacy at Washington State University Spokane.