Objective To evaluate the potential of both jamun (Syzygium cumini) seed and fruit extracts against hyperglycemia. Methods Male Sprague Dawley rats were used to evaluate hypoglycemic potential of jamun extracts. Purposely, jamun fruit and seed's ethanolic extracts based diets were provided to normal and high sucrose diet induced hyperglycemic/diabetic rats for sixty days. The serum glucose and insulin levels were monitored at monthly intervals to evaluate hypoglycemic effect of jamun extracts. Results The results of instant research depicted that both seed and fruit extracts reduce the blood glucose level significantly and also regulate the insulin levels in hyperglycemic rats. It was noted that jamun fruit extract attenuated serum glucose levels to 5.35% and 12.29% in normal and hyperglycemic rats, respectively; while insulin levels were improved by 2.82% and 6.19%, correspondingly. Whereas, jamun seed extract reduced glucose to 7.04% & 14.36% and showed 3.56% & 7.24% higher insulin levels in normal & hyperglycemic rats, respectively. Conclusions The present research revealed that both jamun fruit and seeds have potent prophylactic role against hyperglycemia. In this respect, diet based regimen may be tailored using jamun fruit/seed and their extracts to alleviate hyperglycemia.