This research aimed to determine the chemical composition and identify phenolic components of grape seedless leaves as well as the effect of their biological activity on type 2 diabetic albino rats that were stimulated by Alloxan solution. The rats were equally divided into six groups, seven rats for each group, orally administered daily for 5 weeks and designated as follows, fed with 25% grape leaves (normal control), fed with 50% grape leaves, (diabetic control), diabetic rats fed with 25% grape leaves and diabetic fed with 50% grape leaves. Serum glucose, liver and kidney functions and lipid profile were assessed. The results showed that Flame Seedless grape leaves were an abundant source of crude fiber, total chlorophyll, crude protein, total carbohydrates and total flavonoids as well as total phenols, which have a positive biological effect (p < 0.05) especially for diabetic rats orally fed with 50% grape leaves. Serum glucose levels were significantly different (179.2±0.42) compared to the diabetic control group (243.1±1.17). Lipid profile reached 171.5 ± 1.36 compared to the diabetic control group 187.2 ± 0.49.  The cholesterol level recorded 123.6± 0.87 compared to the diabetic control group 134.7 ± 0.61.   Liver and kidney functions were positively affected in rats that were fed on grape leaves than the control group.