Scientists from a Mexican University researched the effect of papaya leaf on diabetes in 2012.
The study showed that the leaf reduced a “dose-dependent level of glucose in diabetic rats”.
From the Universidad Juàrez Autónoma de Tabasco:
Hypoglycemic Effect of Aqueous Extract of Carica papaya Leaf in Streptzotocin-Induced Diabetic Rats
Isela Juarez Rojop, PhD1, P H Miranda-Osorio, MS1, Teresa Ramon-Frias, MS2, Hidemi Aguilar-Mariscal, PhD1, Jorge Ble-Castillo, PhD1, A Rodriguez-Hernandez, PhD1, Maria A Jimenez-Santos, PhD2 and Juan C Diaz-Zagoya, PhD1