In vivo investigation of the potential hypoglycemic activity of Pennisetum setaceum: Justification of the traditional use among Jordanians Lidia K. Al-Halaseh, Nariman A. Al-Jawabri, Hayat Al-Btoush, Rawan Al-Suhaimat, Siba Majali, Maha N. Abu Hajleh, Ali Al-Samydai, Mai A.M. Ahmed Research Journal of Pharmacy and Technology; 2022; 15(7). Objectives: Pennisetum setaceum has been used traditionally as herbal hypoglycemic and slimming medicine by Jordanians. However, its claimed benefits are still elusive. The current in vivo study aimed to justify the folk use of this herbal tea and evaluate its effect. Materials and methods: plant material was collected from South Jordan and identified. Crude aqueous extract of Pennisetum setaceum aerial parts was prepared. The lethal dose was estimated after given groups of mice oral doses of the herbal extract (1, 2, 4, 6, 8 and 10 g/Kg mouse weight). The potential weight reduction activity was measured by recording the animal weight for 30 days after feeding them 1 g/Kg oral doses of the herbal medicine for 10 consecutive days. The hypoglycemic activity was evaluated in two different concentrations: 1 and 2 g/Kg mouse weight. Male mice with an average weight of 26.5 ± 2.76 g were rendered diabetic by an intraperitoneal dose of streptozocin. Groups of mice were given the herbal medication orally. A negative control group was given d. water. Blood sugar levels were measured from tail blood every 30 min for 3 h. LD50 was estimated. Results: The plant was identified to be P. setaceum by the local authority in Jordan. LD50 was estimated to be 10 g/Kg mouse weight after oral administration. Significant weight reduction of the orally fed group (27 ± 3.1 to 24 ± 2.2) with minor undesirable effects. A significant decrease in blood glucose level in the treated diabetic animals were measured compared with the control group. Significant variation in time-dependent hypoglycemic effect was found between the two tested doses. Conclusion: P. setaceum aqueous extract can be considered as a promising candidate for amelioration of blood sugar profile with potential slimming activity.