Cinnamon is among a number of kitchen spices with a long history of use in treating diabetes, along with cumin, coriander, fenugreek, ginger, mustard seed and turmeric which are all said to have glucose-lowering actions. Prompted by a question in my Twitter feed, I looked at the evidence to see just how effective cinnamon is for helping lower blood glucose levels in people with diabetes. I’ve also reviewed Ayurvedic herbal medicines used to treat prediabetes and type 2 diabetes in a separate post.
Cinnamon and diabetes
Cinnamon bark contains unique, antioxidant polyphenols which can activate insulin receptors so they respond to insulin hormone more effectively. Several studies show that taking cinnamon extracts can reduce average fasting glucose levels, triglycerides and LDL-cholesterol compared with placebo, without causing adverse effects.
Some studies have found less impressive results than others, so a large analysis pooled all the results from 10 trials, involving 543 patients to assess its overall effectiveness. Taking cinnamon doses of at least 120mg per day, for at least 4 weeks, significantly reduced fasting blood glucose levels (by an average of 24.59mg/dL), total cholesterol (by 15.60 mg/dL), ‘bad’ LDL-cholesterol (by 9.42mg/dL) and triglycerides (by 29.59mg/dL) compared with inactive placebo. At the same time, cinnamon increased levels of ‘good’ HDL-cholesterol (which protects against heart disease) by 1.66mg/dL. However, no significant effects were seen on haemoglobin A1c, which measures how well glucose levels have been controlled over the previous 12 weeks.
The most likely explanation is that the studies were of too short a duration to produce a significant response. Even so, the improvements in glucose levels were similar to those seen with some medications used to treat type 2 diabetes (eg sitagliptin) although not as good as those seen with the drug, metformin.
Cinnamon tea and glucose tolerance
A recent study also investigated the effect of drinking cinnamon tea on blood glucose levels in 30 adults without diabetes. The cinnamon tea was made by soaking 60g cinnamon sticks in a litre of water for 24 hours at room temperature, and then heating to 100 degrees for 30 minutes before filtering.
After an overnight fast, volunteers were asked to drink a 100ml dose immediately after 75g glucose solution as part of a glucose tolerance test. In those drinking the cinnamon tea, there was a significant reduction in glucose levels, even though the volunteers did not have diabetes. You can see this in the graph below, where the line with square markers (those taking cinnamon) stays below the line with round markers representing the controls (who did not take cinnamon) throughout the two hours of blood glucose testing.
This is important, as the glucose spike occurring after eating can damage artery linings even in people who normally have good glucose control.
If cinnamon blunts the rise in glucose seen after eating in people without diabetes, it may help those with diabetes, too.
If you like the flavour of cinnamon it’s certainly worth drinking cinnamon tea after a meal if you have diabetes for the beneficial effects on blood fats.
Best cinnamon dose
Researchers have found that doses of 3g cinnamon per day produce a significant reduction in insulin secretion, while 1g has no significant effect. The usual recommended dose is therefore 1g three times a day.
Some supplements contain concentrated extracts so that a lower dose is required (eg 200mg extracts equivalent to 1000mg cinnamon).
Do not exceed manufacturer’s stated dose as cinnamon is toxic in excess. Select cinnamon extracted from Cinnamomum cassia, as the closely related Cinnamomum zeylanicum does not appear to be effective.
NB If you have diabetes, always keep a close eye on your glucose control when taking a supplement. Check with your doctor first, and ensure you know how to adjust your medication if needed.
Chromium picolinate supplements can also improve glucose control.
Click here to read my review of Ayurvedic herbal medicines used to treat type 2 diabetes.
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