The antidiabetic effect of Geigeria alata is mediated by enhanced insulin secretion, modulation of β-cell function, and improvement of antioxidant activity in streptozotocin-induced diabetic rats.

In Sudanese folk medicine, Geigeria alata roots have been used for the management of diabetes for a long time. However, its antidiabetic activity is unreported. In this study, G. alata methanolic extract was tested for its antidiabetic, antioxidant, and β-cell modulatory effects in a streptozotocin-induced diabetic rat model. In this model of diabetic rats, the oral glucose tolerance test with G. alata extract at 125, 250, and 500  mg/kg doses revealed the efficacy of the 250  mg/kg dose in improving glucose tolerance comparable to the standard drug glibenclamide. Diabetic rats were treated with a 250  mg/kg dose of G. alata extract orally for 2  h (acute) or 14 days (chronic). In the case of acute treatment, the extract lowered blood glucose levels significantly at 120  min both in nondiabetic and diabetic rats. Chronic treatment of diabetic rats with 250  mg/kg of G. alata extract resulted in a significant decrease in blood glucose level closer to that of nondiabetic rats. Interestingly, increased serum insulin, improved β-cell function, and antioxidant status were observed in G. alata-treated diabetic rats. G. alata also showed strong antioxidant and α-glucosidase inhibitory activities in in vitro assays. These data show direct evidence that G. alata has antidiabetic activity and suggest that the antidiabetic activity is due to enhanced insulin secretion, modulation of β-cell function, and improvement of antioxidant status.