Diabetes mellitus is a syndrome which affects more and more people in all countries over the world. In México, it is commonly treated with herbal extracts. Such treatment may be of considerable benefit especially during the early stages of the illness. In this review, we discuss species commonly used in México in the treatment of diabetes. A total of 306 species have records of a popular use in the treatment of this syndrome in México. Seven of these species--Cecropia obtusifolia Bertol. (Cecropiaceae), Equisetum myriochaetum Schlecht & Cham (Equisetaceae), Acosmium panamense (Benth.) Yacolev (Fabaceae), Cucurbita ficifolia Bouché (Cucurbitaceae), Agarista mexicana (Hemsl.) Judd. (Ericaeae), Brickellia veronicaefolia (Kunth) A. Gray (Asteraceae), Parmentiera aculeata (Kunth) Seem. (Bignoniaceae)--are discussed in greater detail, highlighting our current knowledge about these botanicals, but also the enormous gaps in our knowledge, most notably as it relates to the species' toxicology, the pharmacokinetics of its active constituents and their metabolism.