Kalanchoe crenata is a vegetable widely used in Cameroon and largely efficient in the treatment of diabetes mellitus. The effect of the water-ethanol extract of this plant (WEKC) on blood glucose levels was investigated in fasting normal and diet-induced diabetic rats (MACAPOS 1) after a short- and medium-term treatment. Diabetes was induced by submitting Wistar rats to a hypercaloric sucrose diet over 4 months. Six hours after a single oral administration of WEKC, 135 and 200 mg kg(-1) body weight extracts significantly (P < 0.01) reduced the blood glucose levels both in normal and diabetic rats without real dose-dependent effect. During the medium-term treatment, 200 mg kg(-1) WEKC administered daily for 4 weeks significantly reduced blood glucose levels within week 1 (P < 0.05), with a maximum effect at week 4 (-52%, P < 0.01), while maintaining glycaemia within the normal range. All the WEKC-treated diabetic rats exhibited significant (P < 0.01) increase in insulin sensitivity index (K (ITT)) compared with the initial time and to the untreated diabetic animals. Animals treated for 4 weeks exhibited a slight resistance in body-weight gain and decrease in food and water intake. The WEKC activities on all parameters assessed were comparable with the glibenclamide effects. Qualitative phytochemical screening revealed that K. crenata contains terpenoids, tannins, polysaccharids, saponins, flavonoids and alkaloids. The data suggest that K. crenata might contain important chemical components that could induce significant improvement in glucose clearance and/or uptake and resistance to body-weight gain and insulin sensitivity, and could be a potent alternative or complementary therapeutic substance in the control of type 2 diabetes and other insulin-resistant conditions.