The trace mineral concentration, phytochemical composition and antidiabetic effect of the ethanol extract of C. lanatus seeds were carried out using standard methods. The preclinical experimental model was 120 mgkg-1 b.w. (via intraperitoneal) Alloxan induced diabetic rat model, with ethanol extract of C. lanatus seeds administered orally at 500mgkg-1 b.w. Qualitative phytochemical screening showed presence of alkaloids, flavonoids, saponins, cardiac glycosides, steroids/triterpenoids, tannins, carbohydrates and oils. Atomic Absorption Spectrophotometric analysis revealed that iron had the highest value (8.31mgkg-1), followed by zinc (5.78 mgkg-1), then manganese (4.28 mgkg-1). Selenium concentration was appreciable (0.85 mgkg-1). Ethanol extract of C. lanatus seeds significantly (p < 0.05), dose and time dependently reduced blood glucose level, increased body weights of rats and had positive effect on organ weights and organ volume. The results in this study showed that Citrullus lanatus seeds are rich in zinc, selenium, manganese, iron, alkaloids, flavonoids, saponins, cardiac glycosides, steroids/triterpenoids, and tannins. They may therefore serve as good sources of these trace mineral nutrients and bio actives for nutritional and medicinal purposes relating to diabetes management.