Ceylon Cinnamon

The Cinnamon That Actually Matters

Walk into any grocery store and the cinnamon on the shelf is almost certainly Cassia — Cinnamomum cassia, the variety grown in China, Vietnam, and Indonesia. It is inexpensive, strongly flavored, and widely available. It is also not what you want if you are supplementing specifically for blood sugar support. The cinnamon that shows up in the most promising diabetes research is Ceylon — Cinnamomum verum, “true cinnamon” — grown primarily in Sri Lanka. The difference matters for both efficacy and safety.

The core mechanism by which cinnamon supports blood sugar is insulin sensitization. Bioactive compounds in cinnamon — primarily cinnamaldehyde and type-A procyanidins — appear to mimic insulin at the cellular receptor level and enhance glucose uptake in skeletal muscle. They also slow gastric emptying, which blunts post-meal glucose spikes by slowing the rate at which carbohydrates enter the bloodstream. This is a different mechanism than most pharmaceutical interventions and works synergistically rather than redundantly with standard diabetes medications.

Ceylon vs. Cassia: The Coumarin Problem

Cassia cinnamon contains roughly 1% coumarin by weight. Coumarin is a natural compound that is toxic to the liver in quantity. The European Food Safety Authority has set a tolerable daily intake for coumarin, and regular use of cassia cinnamon at supplemental doses can exceed that limit. In individuals with pre-existing liver sensitivity, chronic cassia supplementation has been associated with elevated liver enzymes.

Ceylon cinnamon contains approximately 0.004% coumarin — roughly 250 times less than cassia. At standard supplemental doses, Ceylon poses no meaningful coumarin risk. This is the primary safety argument for choosing Ceylon over cassia when using cinnamon therapeutically rather than as an occasional cooking spice.

What the Clinical Evidence Shows

A randomized, double-blind clinical trial in 210 people with type 2 diabetes found that Ceylon cinnamon extract at 250–500mg/day significantly reduced fasting blood glucose compared to placebo. The fasting glucose reduction in the treated group was 78.6 mg/dL versus 11.2 mg/dL in the placebo group — a clinically substantial difference over the study period.

A 2026 review of 28 cinnamon clinical trials found that cinnamon supplementation produced consistent, modest reductions in fasting blood glucose and HbA1c across multiple studies, with the most pronounced effects in people whose baseline glucose was highest. The effect is real but additive — cinnamon works alongside a controlled diet and medication, not instead of them.

Additional findings across trials: reduced triglycerides, modest LDL reductions, and anti-inflammatory effects via inhibition of pro-inflammatory cytokines. Cinnamon also demonstrates antioxidant activity, which is relevant for T2D patients where oxidative stress from chronically elevated glucose contributes to vascular and nerve damage over time.

How to Take It

Dose: 250–500mg of Ceylon cinnamon extract, or 1–2 teaspoons (2–4g) of Ceylon cinnamon powder daily. If buying capsules, verify the label says Cinnamomum verum or Cinnamomum zeylanicum — both are Ceylon. If it says Cinnamomum cassia or Cinnamomum aromaticum, it is cassia.

Timing: With meals, particularly before or during carbohydrate-containing meals. The gastric-emptying-slowing effect is most useful when taken with food.

Interactions: Cinnamon can have an additive effect with diabetes medications, particularly insulin and sulfonylureas. If you are on these medications, monitor blood glucose more closely when starting cinnamon supplementation and discuss with your physician. Hypoglycemia, while rare, is a theoretical concern with additive glucose-lowering interventions.

This page is for informational purposes only and is not medical advice. Consult your physician before making changes to your medications or supplement regimen.