Cinnamaldehyde (also called cinnamic aldehyde) has been well-researched for its effects on blood platelets. Platelets are constituents of blood that are meant to clump together under emergency circumstances (like physical injury) as a way to stop bleeding, but under normal circumstances, they can make blood flow inadequate if they clump together too much. The cinnaldehyde in cinnamon helps prevent unwanted clumping of blood platelets. (The way it accomplishes this health-protective act is by inhibiting the release of an inflammatory fatty acid called arachidonic acid from platelet membranes and reducing the formation of an inflammatory messaging molecule called thromboxane A2.) Cinnamon's ability to lower the release of arachidonic acid from cell membranes also puts it in the category of an "anti-inflammatory" food that can be helpful in lessening inflammation.

Cinnamon may significantly help people with type 2 diabetes improve their ability to respond to insulin, thus normalizing their blood sugar levels. Both test tube and animal studies have shown that compounds in cinnamon not only stimulate insulin receptors, but also inhibit an enzyme that inactivates them, thus significantly increasing cells' ability to use glucose. Studies to confirm cinnamon's beneficial actions in humans are currently underway with the most recent report coming from researchers from the US Agricultural Research Service, who have shown that less than half a teaspoon per day of cinnamon reduces blood sugar levels in persons with type 2 diabetes. Their study included 60 Pakistani volunteers with type 2 diabetes who were not taking insulin. Subjects were divided into six groups. For 40 days, groups 1, 2 and 3 were given 1, 3, or 6 grams per day of cinnamon while groups 4, 5 and 6 received placebo capsules. Even the lowest amount of cinnamon, 1 gram per day (approximately ¼ to ½ teaspoon), produced an approximately 20% drop in blood sugar; cholesterol and triglycerides were lowered as well. When daily cinnamon was stopped, blood sugar levels began to increase. (December 30, 2003)