Purpose: To evaluate the antihyperglycaemic and hypolipidemic effects of Napoleona vogelii Hook. & Planch (Lecythidaceae) methanol leaves extract in alloxan-induced diabetes in rats.

Methods:  The leaves were extracted via cold maceration using 70 % methanol. Diabetes was then induced using alloxan (150 mg/kg I.P). Alloxan-induced diabetic rats were divided into 5 groups of 5 each and were treated with 100, 200 and 400 mg/kg of the methanol extract. The 4th and 5th diabetic groups were given glibenclamide (5 mg/kg) and distilled water respectively. The 6th group, normal rats were given distilled water. Treatment was continued daily and orally for 14 days. Blood glucose levels were monitored at 0, 2, 4, 8 and 24 h, and 14^th days. The lipid profile was determined on the 14th day of administration. Oral acute toxicity and phytochemical screening were also carried out on the extract.

Results: The extract significantly (p < 0.05) reduce fasting blood glucose level at 100, 200 and 400 mg/kg notably from the 4th hour to the 14th day. The effect of the extract compared well with that of glibenclamide which also produced significant reduction (p < 0.05) in blood glucose level in the diabetic rats from the 4th hour onwards. The extract significantly increased and lowered (p < 0.05) High density lipoprotein (HDL)-cholesterol and Low density lipoprotein (LDL)-cholesterol + triglycerides), respectively, at 100 and 200 mg/kg doses. Total cholesterol was also significantly reduced (p < 0.05) at 200 and 400 mg/kg doses. Acute toxicity data revealed death at 4 g/kg dose. While phytochemical screening revealed the presence of flavonoids, saponins, glycosides, tannins and anthraquinones.

Conclusion: These data suggest that Napoleona vogelii leaves have potential hypoglycaemic effect and could be a useful source of an anti-diabetic agent.