According to estimates by the World Health Organization, 537 million people worldwide currently suffer from diabetes, while in Serbia about 770,000 people suffer from diabetes, which is about 12% of the adult population. The high prevalence of diabetes, the severity of the consequences due to the complications of this disease, as well as the side effects of conventional therapy direct the efforts of researchers towards testing plants with antidiabetic potential. The diversity of chemical composition and the traditional use of plants of the genus Morus are the reason for the increasingly frequent examination of the antidiabetic potential of these plants, especially black mulberry, given the rich and diverse biochemical composition. The objectives of this study were: to perform chemical characterization of extracts of bark, leaves, fruits, seeds and juice of black mulberry; to determine the influence of the extracts on the glycemia in healthy animals; to determine the influence of the extracts on the glycemia in animals with streptozotocin induced diabetes, as well as the influence on the preservation of morphological characteristics in the histological structure of pancreatic tissue; to determine the antioxidant potential of black mulberry extracts. The study was conducted on Haan strain NMRI mice. The effect of five different extracts of black mulberry (ethanol extract of leaves, bark, fruit, then freshly squeezed juice and extract of black mulberry or black mulberry seed or black mulberry oil) in three different doses 125 mg/kg, 250 mg/kg and 500 mg/kg in healthy animals was evaluated, as well as the effect of the highest doses of all 5 extracts in animals with streptozotocin-induced diabetes. A high content of isoquercetin (34,8卤0,5 mg/g extract) and rutin (2,7卤0,1 mg/g extract) was found in the leaf extract. Ethanol extract of black mulberry leaf (500 mg/kg) reduced glycemic values compared to the control group in healthy animals. An IC50 value of 7,64 渭g/ml was determined for the leaf extract. The bark extract reduced glycemic values compared to the control group. Also, the application of this extract led to a statistically significant decrease in body weight in relation to the control group (p<0,05). The total proportion of polyphenolic compounds expressed in mgGAE/g was highest in bark extract (68,3卤0,7). Fruit extract (500 mg/kg) reduced glycemic values in healthy animals compared to the control group. Procyanidin B1 (13,8 mg/g of extract) was isolated in the fruit extract, the presence of which has not been determined in other extracts. Black mulberry juice (125 and 250 mg/kg) reduced glycemic values compared to the control group. The presence of cyanidin chloride (7,96卤0,61 mg/g), cyanidin-3-O-glucoside (7,04卤0,54 mg/g) and cyanidin-3-O-rutinoside was detected in the juice (2,10卤0,11 mg/g). Black mulberry seed oil (500 mg/kg) reduced glycemic values compared to the control group. The composition of the oil is dominated by polyunsaturated fatty acids lionolic and oleic with a total share of 88,5%, followed by palmitic 8,6%, stearic 2,5% and arachidonic 0,1% acid. The most potent antioxidant capacity was determined in leaf extract, as well as in bark extract, then seed oil, fruit extract and freshly squeezed juice after FRAP and DPPH analysis. The use of extracts in animals with diabetes led to a decrease in glycemia when ethanol leaf extract (-3,85卤3.60 mmol/l) and freshly squeezed juice (-3.90卤2.80 mmol/l) were used in animal treatment. In the groups treated with bark and fruit extract, and seed oil, the increse in glycemia was detected, while the increase was lower compared to the control group. The use of bark extract decreased body weight in animals with diabetes (-0.32卤3.92 g), while body weight increased in other groups. The activity of the enzymes superoxide dismutase and catalase was significantly higher in the groups of animals treated with leaf and bark extracts compared to the control group (p<0.05). In the group of animals treated with black mulberry oil, a significantly higher superoxide dismutase activity was found in comparison with the control group (p<0.05), while in the group of animals treated with black mulberry juice, a significantly higher activity of the enzyme catalase was found (p<0.05). The intensity of lipid peroxidation was lower in all experimental groups compared to the corresponding control groups. Significantly lower activity was found in the groups treated with black leaf and bark extract, and in the group treated with black mulberry seed oil (p<0.05). Histological analysis of pancreatic tissue verified the protective effect of black mulberry leaf and bark extract. The protective effect was also verified in animals with streptozotocine induced diabetes treated with black mulberry seed oil. Morphometric analysis confirmed the protective effect of the mentioned extracts. Histological analysis of liver tissue revealed a protective effect of leaf and bark extracts, as well as of black mulberry seed oil.