The study is designed to evaluate the Carica papaya effect on diabetes mellitus (DM) and its complications. Ninety clinically healthy white male rats of two months old (100 g average body weight) were divided into equal six groups, each one has 15 rats, Gp. (I): without treatment as normal control, Gp. (II): DM was induced in overnight fasted rats by a single IP injection of Streptozotocin (STZ) (65 mg/kg B.W.) freshly dissolved in 0.1M citrate buffer (pH 4.5), Gp. (III): were received orally a daily dose of C. papaya leaves aqueous extract (0.11 g/ml) by stomach cannula for 30 days, Gp. (IV): were administrated orally a daily dose of C. papaya leaves aqueous extract as in gp. (III) for 40 days. After 10 days post C. papaya treatment the rats were injected by STZ as in gp. (II) then completed C. papaya administration, Gp. (V): DM induced as in gp. (II). Then rats were administrated C. papaya leaves aqueous extract (0.11 g/ml) daily by stomach cannula for 30 days, Gp. (VI): treated like Gp (V) but were administrated C. papaya leaves aqueous extract at a dose level 0.22 g/2ml daily by stomach cannula for 30 days. After 15 days and 30 days post-STZ injection, aqueous leaves extract of C. papaya improved health status of treated diabetic rats, as serum glucose, fractosamine, TC, TGs, LDL-c and MDA activity were decreased, while Insulin and HDL-c levels and CAT activity were increased when compared with untreated diabetic groups.