Cinnamomum Verum
Commonly called Cinnamon.
It enhances glycogen synthesis, increases uptake of glucose, modulating sensitivity and response of insulin.
https://onlinelibrary.wiley.com/doi/full/10.1111/j.1464-5491.2012.03718.x
https://pubs.rsc.org/en/content/articlelanding/2014/fo/c4fo00130c/unauth
Effects of the polyphenol content on the anti-diabetic activity of Cinnamomum Zeylanicum extracts.
https://pubs.rsc.org/en/content/articlelanding/2014/fo/c4fo00130c/unauth