The effect of the water extract (WE) of three medicinal plants used as antidiabetic medication in Eastern Morocco (Arbutus unedo: Au, Ammoides pusilla: Ap and Thymelaea hirsuta: Th) was tested in rats with the Oral Glucose Tolerance Test (OGTT) and Intravenous Glucose Tolerance Test (IVGTT). In the OGTT the rats received water, glibenclamide (2 mg/kg) or WE (500 mg/kg for Au and 250 mg/kg for Th and Ap) 30 min before glucose loading (glucose: 1 g/kg). The WE of Au, Ap and Th produced a significant decrease in glycemia after glucose loading. In the IVGTT the WE of Ap and Th produced a significant decrease in glycemia 60 min after i.v. glucose loading (0.5 g/kg). The addition of the WE of Au (500 mg/kg), Ap or Th (250 mg/kg) induced a significant inhibition of jejunal glucose absorption, (31.6%, 28.5% and 40.5% respectively). This effect could explain in part the significant antihyperglycemic effect observed in the OGTT model but it does not exclude other effects on glucose homeostasis, particularly for Ap and Th. Toxicity tests (high LD50 value) suggest no adverse effect of the use of these plants.