BACKGROUND/AIM: , an endemic Algerian species, has numerous properties, especially as an antidiabetic drug. In Algeria, this herb serves as condiment in Saharan dishes and as animal feed (Sheep, Goat and Camel). However, few scientific studies have reported on the medicinal properties of this Saharan species. The aims of the present work were to study 1) the chemical aspects of polysaccharides extracted from this plant, 2) their inhibitory effect on pancreatic α-amylase in vitro, and 3) their antihyperglycemic effect in streptozotocin-induced diabetic rats in vivo. MATERIALS AND METHODS: First, polysaccharides were extracted from aerial part (ZGAP) in hot water and precipitated with ethanol to obtain ethanolic polysaccharides and with acetone to obtain acetonic polysaccharides. The extracts were characterized using Fourier-transform infrared (FTIR) spectroscopy. In vitro antidiabetic evaluation was performed using pancreatic α-amylase, an enzyme related to diabetes. In addition, ethanolic polysaccharides were tested in vivo in streptozotocin-induced diabetic rats for 4 weeks. The rats received 100 mg/kg ZGAP ethanolic polysaccharides. RESULTS: FTIR spectra showed that ZGAP polysaccharides were heterogeneous in composition, with extraction yield of 14.07 ± 2.61 and 4.48 ± 1.01 g/100 g of dry ZGAP and had a neutral pH (7.03 and 7.2) for ethanolic and acetonic polysaccharides, respectively. Furthermore, ZGAP polysaccharides showed potential as an α-amylase inhibitor, with IC = 3.53 ± 0.09 μg/mL for ethanolic and 7.31 ± 0.42 μg/mL for acetonic polysaccharides. Ethanolic polysaccharides were able to correct hyperglycemia caused by streptozotocin damage. A significant decrease in blood glucose levels and improvement in oral glucose tolerance were observed with ethanolic polysaccharides. Ethanolic polysaccharides extract enhanced the body weight evolution in diabetic rats. CONCLUSION: Based on these findings, we conclude that ZGAP polysaccharides have interesting in vivo and in vitro antidiabetic activities.