Does cinnamon really lower your blood sugar?

Cinnamon probably lowers fasting blood sugar in people with type 2 diabetes by a modest amount. Multiple meta-analyses of randomised trials find an average reduction of roughly 0.5 to 1.4 mmol/L. A recent double-blind study using Ceylon cinnamon extract (1000 mg per day, 12 weeks, n=150) found an average reduction of 8.6 mg/dL compared with placebo. In participants with type 2 diabetes the reduction was as large as 63 mg/dL. That last study was partly funded by a cinnamon manufacturer, which colours the findings.

The crucial caveat lies in the long-term measure of blood sugar control: HbA1c. That is the value doctors use to assess how well blood sugar has been controlled over several months. Older meta-analyses found no improvement in HbA1c with cinnamon. The most recent meta-analysis (24 studies, published up to 2022) did find a modest reduction, but the researchers themselves state that the results are 'not conclusive'. This is because the studies differ widely in dosages, types of cinnamon and study duration.

Cassia cinnamon, the most widely sold variety in supermarkets, contains coumarins. This compound can burden the liver at high daily doses. Ceylon cinnamon contains considerably fewer coumarins and is more often regarded as safer in the research literature. Studies to date are too short and too small to measure rare side effects.

For blood lipids the picture is unclear. Some studies observe a reduction in LDL cholesterol and triglycerides, others do not. No firm conclusion can be drawn here.

Cinnamon is not a replacement for diabetes medication. If you want to try it as a supplement, discuss this with your doctor. Ceylon cinnamon extract has shown a more favourable safety profile in studies than large daily amounts of Cassia cinnamon.