However, usefulness of Opuntia in treating diabetes is not at all resolved. Although some researchers have shown a blood
glucose-lowering effect of
O. streptacantha http://www.ncbi.nlm.nih.gov/pubmed/3276479, another study of three other species of Opuntia (O. lasiacantha, O. velutina, and O. macrocentra) showed no such effect. Yet another study, on O. megacantha, raised concern about toxic effects on the kidney. Well, this last species looks exactly like all the other Nopal's.