Diabetes mellitus (DM) is as a disorder that is characterized by increase in blood sugar levels, as well as disturbances in the metabolism of the three main classes of food. Whole plants or their parts serve as alternatives in the treatment of many diseases and, have, for a time immemorial, been very important in the health care delivery in many countries. The objective of this study was to compare the relative antihyperglycemic properties of Moringa oleifera and Vitex simplicifolia, as well as the reference drug glibenclamide, on blood sugar levels. DM was induced via intraperitoneal injection of alloxan monohydrate; levels of glucose in circulating blood were measured using a glucometer, by tail snip method. Potent oral hypoglycemic properties and thus, a fast onset of anti-diabetic activity was more pronounced in Vitex simplicifolia than in Moringa oleifera. The two were more potent than the reference drug, glibenclamide. The studied leaf extracts are relatively safe and could be used in the treatment of diabetes mellitus.