This study investigated the hypoglycaemic activities of water extract of mistletoe leaf in the management of diabetes mellitus. Male Wistar rats were used for this study and they were housed to acclimatize in five different cages according to their groups. Each group contained four animals. Diabetes was induced in rats in all but groups 4 and 5 following the intravenous injection of alloxan monohydrate (90mg/kg) dissolved in normal saline through rat tail vein. Group 1 diabetic rats were treated with 600mg/kg body weight concentration of crude methanol extract of L. micranthus leaves orally. Group 2 diabetic rats were treated with 600mg/kg body weight concentration of crude water extract of L. micranthus leaves orally. Group 3 diabetic rats were treated with 250mg/kg body weight concentration of glibenclamide orally. Group 4 diabetic rats were not treated and served as positive control. Rats in Group 5, which were non-diabetic, received normal saline and served as negative control. The experiments were repeated using different Wistar rats for groups 1, 2, and 4 for the second, third, and fourth weeks. The results of this study showed that both the methanol and aqueous extracts of L. micranthus leaves significantly (P<0.05) reduced mean fasting blood sugar concentrations in normal rats. In diabetic rats, both extracts caused a significant (P<0.05) reduction in serum glucose levels.