Diabetes mellitus affects a significant proportion of the population worldwide. Dietary supplements, such as pomegranate juice (PJ), may contribute to prevent diabetic complications improving antioxidant status. Nowadays, pomegranate is among the most popular fruits due to its numerous health benefits. The composition of the pomegranate is strongly dependent on the cultivar, growing region, climate, maturity and cultivation practices. The genetic variability of pomegranate is a valuable asset to breed cultivars expressing specific functional compounds demanded by the consumer and the medical science. The aim of this work was to evaluate four selected cultivars differing in aril color; red and deep red, and juice acidity; sweet and tart, to explore its effect on juice composition and protective effects on the kidneys of diabetic Wistar rats. Physicochemical characteristics, total phenol content, tannins, anthocyanins, total flavonoids, and antioxidant activity (ABTS assay) were evaluated. The results indicate that dark red juice showed higher phenolic content than the lighter colored. The individual phenols identified were gallic acid, protocatechoic acid, benzoic acid, epigallocatechin-3-gallate. Dark juices also showed higher antioxidant activity with the ABTS method; and for this reason we evaluated their protective effect in a diabetes animal model induced with streptozotocin. Pomegranate juice (2%) was administered during 4 weeks. Fasting glucose levels, lipid profile and kidney damage parameters were measured (glucose, creatinine and protein in urine; protein and lipid oxidation in kidney). The results indicated that the juice from the selection dark red and sweet reduced 11% the blood glucose levels. Both dark selections reduced total cholesterol (28% reduction), and increased HDL levels (33% increase) and protected against oxidative damage. The juice of the pomegranate selections could be considered an adjuvant therapy for diabetes and its complications.