BACKGROUND Malmea depressa is traditionally used in the Mayan communities of southeastern Mexico to treat type 2 diabetes. A root bark infusion is being taken throughout the day, between meals. OBJECTIVE The aim of this study was to determine whether an ethanolic extract of Malmea depressa would reduce hepatic glucose production by targeting gluconeogenesis. The effects of the plant extract on gluconeogenesis (in vivo) and the activity of GL-6-P (in vitro) were examined. METHODS The plant extract was analyzed by HPLC to confirm its phytochemical composition. The inhibition of gluconeogenesis was tested in vivo by performing a pyruvate tolerance test in n5-STZ after an 18-h fasting period. The extracts effect on glucose-6-phosphatase activity were assayed in vitro with intact rat liver microsomes. RESULTS Using HPLC-DAD we confirmed that the phytochemical compositions of the tested extract were similar to those previously reported. We proved that the ethanolic extract of the root bark of Malmea depressa dose-dependently inhibits a glucose peak. Furthermore, the gluconeogenesis inhibition was confirmed in vitro using a pyruvate test. CONCLUSIONS The results suggest that administration of Malmea depressa can improve glycemic control by blocking hepatic glucose production, especially in the fasting state. These data support its traditional use as an infusion consumed continually throughout the day.