There is a general lack of adequate methods to quantitatively assess the importance of specific medicinal plants in a culture. In Mexico like in many other countries type 2 diabetes is an increasing health problem and the use of medicinal plants to treat this disease is widespread. In the present study we propose a mathematical tool for analysing ethnopharmacological field data, with the ultimate aim to select species with most prominent impact on a community to treat a single disease. Using this tool in a Yucatec Mayan community we demonstrate that Malmea depressa (Baill.) R.E. Fr. and Cecropia peltata L. are culturally most salient hypoglycemic plants in this community.