Diabetes mellitus is a global epidemic, and India being the major epicenter of it. However, many synthetic drugs are available in the market. But produce specific side effects or residual effects. The concept of plant-based inhibitors has come up to overcome the adverse effects of synthetic drugs. Plant-derived inhibitors are less toxic, have minimal side effects, and are easily adaptable by the human body. Sequential solvent extraction of Premna herbacea leaves was carried out to evaluate the in-vitro and in-vivo anti-diabetic properties against streptozotocin (STZ) induced Wister albino diabetic rats. Among all the extracts, methanol showed the highest inhibitory potential of α-amylase (IC50 68.62 ± 2.11) and α-glucosidase (IC50 75.01 ± 2.40) significantly in comparison to standard acarbose. The toxicity, carbohydrate tolerance, and biochemical parameters among the experimental animal groups were performed using the methanol extract. The methanol extract showed no toxicity and side effects. It had significant tolerance against glucose, maltose, and starch compared to the diabetic control and standard groups. The methanol extract has shown effective results in controlling body weight loss, decreased blood glucose level, and other biochemical parameters like cholesterol, triglycerides, and glycosylated hemoglobin. The in-vitro and invivo results suggested that the methanolic Premna herbacea leaves extract is a dosedependent inhibitor of α-amylase and α-glucosidase in managing type 2 diabetes mellitus. Furthermore, the GC-MS analysis validates the hypoglycemic property of Premna herbacea by reporting the presence of major active anti-diabetic compounds like Beta-Sitosterol, Octadecenoic Acid, Triacontanoic Acid, Phytol, Methyl Eicosatetraenoate, Stigmasterol, Thymol, and D-Mannitol.