Q. I've heard that you can treat diabetes by taking an extract from cinnamon. I suspect this is snake oil, but is there anything to it?
A. A few years ago, I heard the same thing from a friend. My first reaction was like yours, but my friend was knowledgeable about food and suffered from type 2 diabetes, so I looked into it. There have been several published scientific studies — randomized, placebo-controlled trials — of cinnamon in patients with type 2 diabetes or prediabetes. Most involved relatively few people (between 20 and 60) and lasted a short time (a few weeks). A slight majority showed that cinnamon reduced blood sugar more than placebo, but the other studies didn't show a benefit.
Whenever some improbable treatment is reported to work, and I'm not sure I believe it, I look for a biochemical explanation. With cinnamon and diabetes, there is one, and it involves glucose, insulin, and insulin receptors.
Glucose is the simple sugar that circulates in the blood. All cells depend on it for energy, so glucose needs a way to get from the bloodstream into cells. Insulin is a hormone that also circulates in the blood. When insulin attaches to structures on the outside of cells called insulin receptors, it's as if doors to the cells swing open and glucose is allowed in. In people with type 2 diabetes, cells resist this effect of insulin, so glucose doesn't get into cells and builds up in the blood instead.
Cinnamon contains several chemicals that stimulate insulin receptors so glucose can get into cells and that means levels in the blood go down. There's some debate about exactly which chemicals are the critical ones.
So cinnamon as a treatment for diabetes may not be pure snake oil. But hang on. I also think studies with many more people for longer periods of time need to be done before we get too excited about this "natural" treatment. My guess is that cinnamon and other foods may have some value in treating type 2 diabetes, but probably as adjuncts to, rather than as substitutes for, conventional medicine.
— Anthony L. Komaroff, M.D.
Editor in Chief, Harvard Health Letter