http://www.metpet.com/Reference/Health/cinnamon for diabetic pets.htm
I did a search, this site says it mimics insulin. I would probably want to see a study with cats prior to using it.
The fact that it mimics insulin is a bit scary. And how do you scale it down from human dose to a cat dose.
So I'm a dietitian with a master's degree in nutrition and here's what I know: 1/4 tsp a day of cinnamon has been known to help with blood sugar control in humans. I think it's a big stretch to claim that it mimics insulin because we don't really know the mechanism of why it works. The only thing I know of that truly "mimics" insulin is excercise and that is because it activates calcium channels in the cells that allows glucose to enter from the bloodstream. Now I'm not advocating you put your kitty on a treadmill because this effect is small. My boyfriend is actually a type 1 diabetic and he could exercise all day long but if he didn't have insulin he would die.
Like the poster before, I'd be wary of adding cinnamon to my cat's diet without a solid study showing that it's safe. From ASPCA website, it says it's non-toxic but who knows if we were to give it regularly? "Large overdoses of the powder or exposure to the essential oil can lead to low blood sugar, liver disease, vomiting, diarrhea and changes in heart rate." http://www.petpoisonhelpline.com/2013/1 ... -toxicity/