BACKGROUND Traditional medicine is used by over 60% of the world's population for health care. Mukia maderaspatana (L.) M. Roem. (Cucurbitaceae) (Mukia) is extensively used in folklore medicine as an antidiabetic plant. It is rich in phenolics that contribute to its medicinal properties. OBJECTIVE Mukia extract and phenolics such as quercetin and phloroglucinol are investigated for their in vitro antidiabetic activity. METHODS Quercetin, phloroglucinol, and methanol extract of the dried whole plant (0.25 and 0.5 mg/ml) were studied for the inhibition of gluconeogenesis in rat liver slices and glucose uptake in isolated rat hemi-diaphragm (50 and 100 µg/ml). Phenolics of Mukia were analyzed by HPLC. CONCLUSIONS Glucose (1.2 mg/g/h) was synthesized from pyruvate and the synthesis was completely inhibited by insulin (1 U/ml). Quercetin at 0.25 and 0.5 mg/ml caused 65% and 89% inhibition (0.42 mg/g/h and 0.13 mg/g/h glucose). Addition of insulin did not increase inhibition. Phloroglucinol inhibited 100% glucose production with or without insulin. Mukia (0.25 mg/ml) inhibited gluconeogenesis (0.65 mg/g/h) by 45%, and with insulin, inhibition increased to 50% (0.59 mg/g/h). At 0.5 mg/ml, glucose production was stimulated by1.2-fold, but with insulin it was inhibited by 89% (0.13 mg/g/h glucose). Mukia had no effect on glucose uptake, but potentiated the action of insulin mediated glucose uptake (152.82 ± 13.30 mg/dl/g/30 min) compared with insulin control (112.41 ± 9.14 mg/dl/g/30 min) (p < 0.05). HPLC analysis revealed the presence of phenolics. CONCLUSIONS Results provide scientific rationale for the use of Mukia in folk medicine as an antidiabetic nutraceutical.