Metformin is a chemically modified derivative of guanidines found in the French hellebore plant.

“Metformin is a remarkable molecule, comes from the plant world, is very simple. The French hellebore or lilac plant produces what's called guanidines, and these have been known to treat diabetes for many years, in fact, over a century, and then chemists have put methyls on them, chemically modified it so that it's more stable. We call this Metformin and that's what we have as the drug today.”